What are two ways that iOS differs from Android A Comparative Glance

What are two ways that iOS differs from Android? Embark on a journey through the digital landscape, where the paths of iOS and Android diverge, shaping the way billions experience technology. This isn’t just about operating systems; it’s about two distinct philosophies, each offering a unique take on how we interact with our digital lives. Imagine them as twin siblings, sharing the same bloodline but with vastly different personalities, aspirations, and approaches to the world.

Delving into the core, we find the user interface and experience – a realm where iOS embraces sleek simplicity, guiding users with an intuitive hand, while Android opens its doors to boundless customization, inviting exploration and personalization. Furthermore, consider the ecosystems and app availability. The App Store and Google Play Store, each a vibrant marketplace, present a world of possibilities.

Yet, the review processes, the exclusive apps, and the integration with hardware subtly shape our experiences. From the tight-knit world of Apple’s hardware-software marriage to the sprawling Android landscape, the nuances are as captivating as they are fundamental.

Table of Contents

User Interface and Experience: What Are Two Ways That Ios Differs From Android

The user interface (UI) and user experience (UX) are the battlegrounds where iOS and Android regularly clash. These are not just about aesthetics; they define how you interact with your device daily. The core philosophies behind each operating system’s design shape everything from navigation to app organization and notification management. These differences influence user preferences and create distinct ecosystems.

Navigation Philosophies

Navigating your smartphone is a fundamental interaction, and iOS and Android approach this in different ways. These varying methods influence how users move through apps, access settings, and manage their devices.iOS relies heavily on a gesture-based navigation system. Swiping is king. Swiping up from the bottom of the screen typically takes you home, swiping from the left edge often navigates back, and swiping down from the top right reveals the Control Center.

This intuitive system is generally consistent across all apps, providing a seamless and fluid experience.Android, on the other hand, historically used on-screen navigation buttons (back, home, and overview/recents). While many Android phones now also offer gesture navigation, the button-based approach remains a viable option, giving users more control over their preferred method. Gesture navigation on Android often involves swiping from the edges or bottom of the screen, similar to iOS, but the specific gestures can vary slightly depending on the manufacturer.

The core concept is the same, but the implementation can differ.

App Organization

How you arrange your apps on your home screen is a significant aspect of personalization. iOS and Android offer different levels of customization and control.iOS utilizes a straightforward, grid-based system for app organization. All apps are displayed on the home screen or in the App Library. Users can arrange icons by dragging and dropping them, creating folders to group related apps.

The App Library, introduced in iOS 14, automatically categorizes apps, making it easier to find what you need without cluttering the home screen. While the level of customization is limited compared to Android, the simplicity is a strength for many users.Android offers far more flexibility in terms of app organization. Users can place widgets, which display real-time information (like weather or calendar events), directly on the home screen.

They can customize the size and placement of icons, and install third-party launchers for even more advanced customization options. This level of control allows Android users to tailor their home screens to their exact preferences.

Notification Systems

Notifications are a constant presence on smartphones, and both iOS and Android have robust systems for managing them. Each platform offers unique features and approaches.iOS features a notification system that groups notifications by app and displays them on the lock screen and in the Notification Center. Users can customize notification settings for each app, choosing alert styles (banners, alerts, or none) and whether to show notifications on the lock screen.

Focus modes allow users to filter notifications based on their activity or time of day, minimizing distractions.Android’s notification system is known for its flexibility and customization. Notifications appear at the top of the screen and can be expanded for more information or interacted with directly (e.g., replying to a message). Users can prioritize notifications, categorize them by importance, and snooze them for later.

Notification channels allow granular control over how each app delivers notifications, providing a high degree of customization.

Key Visual Distinctions in the UI

The visual differences between iOS and Android extend beyond just the layout of the home screen and app organization. Elements such as icons, widgets, and animations contribute to the overall user experience. The following table provides a comparative overview:

Feature	iOS	Android	Description
Icons	Generally use a consistent, rounded-corner square shape. Often feature a clean, minimalist design.	More varied icon styles, often following the design language of the device manufacturer (e.g., Samsung, Google Pixel). May include more gradients and subtle shadows.	Icons serve as visual cues for applications, their shape, style and design can affect user’s perception of the operating system.
Widgets	Widgets are available, but historically less prominent and customizable than on Android. Often have a simpler, more streamlined design.	Widgets are a core feature, offering a wide range of sizes, shapes, and functionalities. Users can place them anywhere on the home screen.	Widgets allow users to access and interact with information from apps without opening them. They can be customized and rearranged.
Animations	Animations are smooth and consistent, emphasizing a sense of fluidity and responsiveness. Transitions are generally subtle and designed to be unobtrusive.	Animations are more customizable, with varying speeds and styles depending on the device and manufacturer. Transitions can be more dynamic and pronounced.	Animations provide visual feedback and enhance the user experience by making interactions feel more natural and intuitive.
System Fonts	Uses the San Francisco font, designed by Apple for optimal readability and a consistent look across all devices.	Uses a system font (e.g., Roboto or Google Sans) that may vary depending on the device manufacturer. Offers more customization options.	Fonts contribute to the overall visual aesthetic and readability of the user interface.

Ecosystem and App Availability

The digital worlds of iOS and Android are like two bustling cities, each with its own unique infrastructure and offerings. These ecosystems, built around their respective app stores, dictate not only what apps you can access but also how they function and integrate with your device. Let’s delve into the fascinating differences in these app marketplaces and how they shape the mobile experience.

App Store Dynamics: iOS vs. Google Play

The iOS App Store and Google Play Store are the central hubs for acquiring applications on their respective platforms, but their operational philosophies differ significantly. The impact of these differences affects the types of apps available, the security of user data, and the overall user experience.The iOS App Store, known for its stricter review process, tends to have a reputation for offering a more curated selection of apps.

Apple’s rigorous screening aims to ensure that apps meet specific quality standards and adhere to their guidelines. This process includes checks for functionality, security, and adherence to privacy policies. As a result, users often perceive the App Store as a safer environment, with fewer instances of malicious software. However, this stringent approach can sometimes lead to longer app approval times and, occasionally, the rejection of innovative apps that don’t quite fit Apple’s mold.Conversely, the Google Play Store adopts a more open approach.

While Google also reviews apps, the process is generally less restrictive than Apple’s. This allows for a wider variety of apps to be available, including those that might not meet Apple’s stringent criteria. This open nature fosters innovation and provides developers with more flexibility. However, it also means that users need to be more vigilant about app security and the source of their downloads.

This can sometimes lead to the presence of apps that are poorly designed, contain malware, or violate user privacy.

Cross-Platform App Availability and Exclusivity

The availability of apps across platforms is a key factor in choosing a mobile operating system. While many popular apps are available on both iOS and Android, there are instances of exclusivity and feature variations that can sway user preference.Exclusive apps can be a significant draw for users. For example, certain games or productivity tools might launch exclusively on iOS or Android for a period or indefinitely.

These exclusives can provide a competitive edge, attracting users who desire a specific app or feature unavailable on the other platform.Feature parity is another consideration. Even when apps are available on both platforms, feature sets can differ. Developers may prioritize features for one platform over the other, or certain hardware integrations might be exclusive to a particular operating system. This can lead to a fragmented user experience, where the functionality of an app varies depending on the device.

Hardware-Software Integration’s Impact on App Functionality

The tight integration of hardware and software is a hallmark of the iOS ecosystem. Apple designs both the hardware and the software, enabling seamless communication and optimization. This integration allows for features that are difficult or impossible to replicate on Android, where hardware is produced by various manufacturers.For example, features like the iPhone’s advanced camera capabilities, including computational photography and optimized image processing, are often attributed to this close integration.

The software is specifically tailored to the hardware, resulting in superior performance. Similarly, features like the Apple Watch’s health tracking capabilities are tightly integrated with iOS, offering a cohesive user experience.In contrast, Android’s open nature and diverse hardware ecosystem mean that app developers need to account for a wide range of devices and specifications. This can sometimes lead to compromises in app functionality, as developers must ensure compatibility across different hardware configurations.

However, this also encourages innovation, as developers create apps that can work across a broad spectrum of devices.

Common Cross-Platform Apps with Feature Variations

Many of the most popular apps are available on both iOS and Android. However, feature variations can exist, affecting the user experience.Here are some examples:

Social Media Apps: Apps like Instagram and Facebook are available on both platforms. However, they may receive updates and new features at different times. For instance, a new filter on Instagram might appear on iOS before Android.
Messaging Apps: WhatsApp, Telegram, and Signal are available on both iOS and Android. While the core functionality remains the same, specific features, such as the user interface or certain privacy settings, might vary slightly.
Productivity Apps: Microsoft Office and Google Workspace (Docs, Sheets, Slides) are available on both platforms. While the core functionality is consistent, some features, such as advanced formatting options or integration with device-specific features, may vary.
Streaming Apps: Netflix, Spotify, and YouTube are available on both iOS and Android. While the basic functionality is similar, the user interface and features such as offline downloads or background playback might differ slightly between the two platforms. For example, Spotify might offer a slightly different interface on Android compared to iOS.
Gaming Apps: Games like “Fortnite” and “PUBG Mobile” are designed for both platforms. However, graphics and performance might be optimized differently, depending on the device. iOS devices, with their unified hardware, may offer more consistent performance compared to the more varied Android hardware.

Customization and Openness

The world of mobile operating systems is a vibrant landscape, and the choices between iOS and Android often hinge on personal preferences. One of the most significant distinctions lies in the level of customization and openness each platform offers. This is where the true character of your device, and how you interact with it, is ultimately defined.

Customization Capabilities: iOS vs. Android

The battleground of personalization is fiercely contested, with Android holding a clear advantage. iOS, known for its polished and streamlined experience, has historically prioritized a more controlled approach to user customization. This is not necessarily a bad thing; it ensures consistency and a certain level of user-friendliness across all devices. However, Android embraces a philosophy of open access, providing users with far more granular control over their device’s appearance and functionality.Let’s delve deeper into these differences:* Theming Options: Android allows users to completely overhaul the look and feel of their device.

This includes changing the system-wide color palettes, icon packs, fonts, and even the animation styles. You can transform your device to mimic other operating systems, or create a truly unique aesthetic. On iOS, theming is much more limited. While you can adjust some aspects of the display, such as the dark mode, and change the wallpaper, you’re essentially locked into Apple’s design language.* Launchers: Android launchers are the gateway to a world of personalization.

They allow you to replace the default home screen, app drawer, and overall interface. This means you can completely redesign how you interact with your phone. Popular launchers like Nova Launcher and Action Launcher offer a wealth of features, including custom gestures, icon packs, and widget arrangements. iOS, on the other hand, restricts users to the default home screen layout, with limited options for customization.

You can rearrange icons, use widgets, but you cannot change the underlying launcher.* Widgets: Widgets are a core component of customization. They provide at-a-glance information and quick access to app features. Android has long embraced widgets, allowing users to place them anywhere on the home screen and customize their size and appearance. iOS has gradually improved its widget support, but it’s still more restrictive.

Widgets are confined to a dedicated area on the home screen, and customization options are generally more limited.

File Management Systems: A Comparative View

The way you manage your files on your phone is an often-overlooked aspect of the mobile experience, but it’s a crucial element in determining how much control you have over your data.* iOS File Management: iOS has a more restrictive file management system. The Files app is the central hub, allowing you to access and manage files stored locally, in iCloud, or in other cloud storage services.

However, access to the underlying file system is limited. This means that you can’t easily access or modify system files, which helps to maintain the security and stability of the operating system.* Android File Management: Android provides a more open and flexible file management system. A built-in file manager, or third-party apps, gives users direct access to the device’s file system.

You can browse, copy, move, and delete files in various folders, including those related to system processes (though modifying system files is generally not recommended). This level of access gives Android users greater control over their data, but it also means they need to be more cautious about the files they handle.

The Impact of Open Source: Software Updates on Android

The open-source nature of Android, built upon the Android Open Source Project (AOSP), has significant implications for software updates. This is a double-edged sword, offering both advantages and disadvantages.* Faster Updates for Some: Because Android is open source, device manufacturers can customize the operating system to fit their hardware. This also means that some manufacturers are more proactive in releasing software updates.

Google’s own Pixel phones are generally the first to receive updates, followed by other manufacturers like Samsung, OnePlus, and others.* The Fragmentation Issue: The open-source nature has also contributed to fragmentation. Many manufacturers are slow to roll out updates, and some older devices may never receive them. This is often due to the cost and complexity of adapting the latest version of Android to a specific device.* Security Implications: Delayed updates can also have security implications.

Security patches are often included in software updates. Without these patches, devices can be vulnerable to security threats.Here’s a breakdown of specific customization options available on Android but restricted on iOS:

Custom Launchers: Replace the entire home screen interface with a completely different look and feel.
Icon Packs: Change the appearance of all app icons on the device.
System-Wide Themes: Apply themes that change the color scheme, fonts, and overall design of the operating system.
Custom Widgets: Use widgets from third-party apps, with greater flexibility in size, placement, and customization.
Root Access: Gain advanced control over the operating system, allowing for extensive customization and modification (though this can void warranties and introduce security risks).
File Manager Access: Browse and manage files stored on the device with greater freedom.

Hardware and Software Integration

The harmony between hardware and software is a critical differentiator in the mobile world. iOS devices, known for their streamlined ecosystem, benefit immensely from this close integration, leading to a consistently smooth and optimized user experience. Android, on the other hand, operates in a more diverse environment, which presents both advantages and disadvantages in this crucial area.

Hardware and Software Synergy

Apple designs both the hardware and the software (iOS) for its iPhones and iPads. This allows for a level of optimization that’s difficult to replicate. Imagine a symphony orchestra where every instrument is perfectly tuned and plays in perfect harmony. This is the essence of Apple’s approach. They control everything, from the processor to the operating system, ensuring seamless performance.

The A-series chips in iPhones are specifically designed to work with iOS, resulting in exceptional power efficiency and performance. For example, features like the Neural Engine in the A15 Bionic chip are deeply integrated with iOS to enhance machine learning tasks, leading to faster processing and improved battery life.
iOS is optimized for the specific hardware components of each iPhone model. This means that features like the camera, display, and haptic engine are finely tuned to deliver a consistent and high-quality experience across all supported devices.
Apple can introduce features that leverage specific hardware capabilities in ways that Android manufacturers often cannot. Think about the ProMotion display technology in recent iPhones, which dynamically adjusts the refresh rate for smoother scrolling and animations. This feature is possible because Apple controls both the display hardware and the software that controls it.

Software Update Processes

The update process is another significant area where the differences between iOS and Android become apparent. It’s like comparing a well-organized train system to a network of independent bus routes.

iOS updates are typically released simultaneously to all compatible devices. This ensures that users receive the latest features, security patches, and performance improvements at the same time, regardless of their iPhone model (within a supported range).
Android updates, however, are often delayed and fragmented. This is because Android is an open-source operating system used by numerous manufacturers, each with its own hardware and software customizations. The update process involves several steps, including Google releasing the update, manufacturers adapting it for their devices, and carriers testing and distributing it. This process can take months, leaving some devices vulnerable to security threats for extended periods.
The consequence of this fragmentation is that older Android devices may never receive the latest updates, or they may receive them long after they are released. This can lead to security risks and a less consistent user experience.

Hardware-Specific Feature Examples

Let’s delve into some examples to illustrate how each platform utilizes hardware in distinct ways. Consider this: Apple’s tight control allows for innovations that are deeply integrated with the hardware, whereas Android’s open nature fosters a broader range of hardware capabilities across various devices.

iPhone’s LiDAR Scanner: The LiDAR scanner on recent iPhones is tightly integrated with iOS for augmented reality (AR) applications. It enables faster and more accurate depth sensing, allowing for more realistic AR experiences, such as measuring the height of a room or creating 3D models of objects.
Android’s Foldable Devices: Android has embraced foldable phones with a focus on optimizing the user experience across the various screen sizes and form factors. This includes features like app continuity, which allows apps to seamlessly transition between the folded and unfolded states.
iPhone’s Haptic Engine: Apple’s Taptic Engine provides precise and nuanced haptic feedback, enhancing user interactions. The integration of this hardware component with iOS allows for subtle and responsive vibrations, creating a more immersive experience.
Android’s Customizable Hardware: Android allows manufacturers to integrate unique hardware features, such as specialized camera sensors or stylus support. This provides users with a wide range of choices, but it can also lead to inconsistencies in software support and performance.

Update Frequency and Support Lifecycle Comparison

The following table provides a comparative analysis of the update frequency and support lifecycle for iOS and Android devices. It’s like comparing the longevity of a classic car to the fast-paced evolution of a modern electric vehicle.

Feature	iOS	Android
Update Frequency	Typically released simultaneously for all compatible devices.	Varies significantly by manufacturer and device model. Often delayed or fragmented.
Update Duration	Generally, devices receive software updates for 5-7 years.	Support duration varies widely, from a few months to several years, depending on the manufacturer and device.
Security Updates	Regular and timely security updates for all supported devices.	Can be inconsistent, with older devices often receiving delayed or no security updates.
Software Version Consistency	High: Most users are on the latest iOS version.	Low: Significant fragmentation, with many devices running older Android versions.

Security and Privacy

In today’s digital landscape, the security and privacy of our personal information are paramount. Both iOS and Android have invested heavily in creating robust security architectures, but they approach these challenges with distinct philosophies. These differences are crucial for users to understand when choosing a mobile platform, as they directly impact how their data is handled and protected.

Security Models: Sandboxing and Permissions Management, What are two ways that ios differs from android

iOS and Android implement different approaches to app security, particularly concerning sandboxing and permission management. This influences how applications interact with the device and user data.iOS employs a highly restrictive sandboxing model. Each app operates within its own isolated environment, preventing it from accessing other apps’ data or system resources without explicit permission. This “walled garden” approach significantly limits the potential damage a malicious app can inflict.Android, while also using sandboxing, offers a more flexible system.

Apps request permissions to access specific resources like contacts, location, or the camera. Users are prompted to grant these permissions during installation or at runtime. While this allows for greater functionality, it also increases the potential attack surface if users inadvertently grant permissions to untrustworthy apps.Here’s a quick comparison:

iOS: Highly restrictive sandboxing; apps cannot access other apps’ data without explicit permission. Permissions are generally granted at install time.
Android: Sandboxing with more flexibility; apps request permissions for specific resources. Users can grant permissions at install or runtime.

Privacy Features and Data Handling Practices

Both iOS and Android have integrated privacy features, but they vary in their implementation and the level of user control offered. Understanding these differences is essential for making informed choices about data privacy.iOS is known for its strong focus on user privacy. Apple’s data handling practices emphasize minimal data collection and transparent disclosure. Features like App Tracking Transparency, introduced in iOS 14.5, give users the ability to control how apps track their activity across other apps and websites.

Users can easily opt out of tracking, limiting the data that apps can collect for personalized advertising. Furthermore, Apple has implemented features like Private Relay for iCloud users, which masks the user’s IP address and browsing activity, enhancing online privacy.Android, while also committed to user privacy, offers a different approach. Google provides extensive tools for managing privacy settings within the Google account.

Users can review and control the data collected by Google services, including location history, search activity, and YouTube watch history. Android also provides granular control over app permissions, allowing users to review and revoke permissions at any time. However, the open-source nature of Android allows for more variation in data handling practices across different manufacturers and app developers.Here are the key points:

iOS: Emphasizes minimal data collection, transparent disclosure, and features like App Tracking Transparency. Offers Private Relay for iCloud users.
Android: Provides tools for managing privacy settings within the Google account, with granular control over app permissions. Data handling practices can vary based on manufacturer and app developer.

User Data and App Permissions: Transparency

The way iOS and Android handle user data and app permissions differs, particularly in terms of transparency. Both platforms aim to inform users about what data is being collected and how it is being used, but their methods vary.iOS offers detailed privacy reports within the App Store, providing users with information about an app’s data collection practices. This includes what data is collected, how it is used, and whether it is shared with third parties.

This information is designed to be easily accessible and understandable, enabling users to make informed decisions about which apps to download and use.Android uses a different approach. Before installing an app, users are presented with a list of the permissions the app requests. While this provides some transparency, the user must interpret the meaning of these permissions. Google is continually working to improve transparency, including providing more information about how apps use the requested permissions.Here’s how they compare:

iOS: Detailed privacy reports in the App Store, highlighting data collection practices.
Android: Lists app permissions before installation; ongoing efforts to improve transparency.

Unique Security Features

Each operating system boasts unique security features designed to protect user data and privacy. These features reflect the different design philosophies and priorities of Apple and Google. iOS Unique Security Features:

App Tracking Transparency: Requires apps to ask for permission before tracking user activity across other apps and websites.
Private Relay (iCloud+): Masks the user’s IP address and browsing activity.
End-to-end encryption for iMessage and FaceTime: Ensures that messages and calls are only accessible by the sender and recipient.
Regular security updates: Apple has a strong track record of quickly releasing security patches to address vulnerabilities.
Secure Enclave: A dedicated hardware security module for storing sensitive data like Touch ID and Face ID information.

Android Unique Security Features:

Google Play Protect: Scans apps for malware and other security threats.
Verified Boot: Ensures that the operating system is running a trusted version.
Regular security updates from Google and device manufacturers: Security updates are pushed regularly to address vulnerabilities, though the frequency can vary.
Scoped Storage: Restricts apps’ access to user files, enhancing privacy.
Customizable Permissions: Offers more granular control over app permissions.

Software Updates and Fragmentation

The world of mobile operating systems is constantly evolving, with new features, security patches, and performance enhancements regularly being released. However, the path to receiving these updates varies dramatically between iOS and Android, creating a fragmented landscape that impacts user experience and device security. This difference in approach is a key differentiator between the two platforms, affecting everything from how quickly you get the latest features to the overall lifespan of your device.

Update Process Variations

The update process for iOS is streamlined and straightforward, managed entirely by Apple. When a new version of iOS is released, it becomes available simultaneously for all compatible iPhones and iPads. This centralized control allows Apple to ensure a consistent update experience across its entire device lineup.In stark contrast, Android updates are significantly more complex. The process involves multiple players: Google, the silicon manufacturer (like Qualcomm or MediaTek), and the device manufacturer (Samsung, Google, Xiaomi, etc.).

When Google releases a new Android version, it first provides the source code to the silicon manufacturers, who then optimize it for their specific processors. Device manufacturers then take this optimized code, customize it with their own user interface (UI) and pre-installed apps, and finally, push it out to their devices. This multi-layered process introduces delays and fragmentation.

Speed and Consistency of Updates

iOS devices are known for receiving updates quickly and consistently. Apple’s control over both the hardware and software allows for rapid deployment. Typically, the majority of iPhones and iPads will be running the latest version of iOS within a few months of its release. This swiftness means users benefit from the newest features, improved security, and optimized performance sooner rather than later.Android, however, suffers from a notable lag in update deployment.

The fragmentation inherent in the update process leads to significant delays. The speed at which updates are released varies greatly depending on the manufacturer and the device model. Some manufacturers, like Google with its Pixel phones, prioritize timely updates, while others are considerably slower. This disparity means some Android users may wait months, or even years, to receive the latest Android version, if they receive it at all.

This inconsistency can leave older devices vulnerable to security threats and missing out on the latest advancements.

Android Manufacturer Management

Android manufacturers manage updates differently, contributing to the platform’s fragmentation.

Google (Pixel): Google’s Pixel phones receive updates directly from Google and are usually the first to get the latest Android versions, often within days or weeks of release. This provides a consistent and timely update experience.
Samsung: Samsung, the largest Android manufacturer, has improved its update practices in recent years. While still not as swift as Apple, Samsung has committed to providing updates for a longer period and is generally quicker than many other Android brands.
Other Manufacturers (Xiaomi, OnePlus, etc.): The update speed and consistency vary significantly among other Android manufacturers. Some offer timely updates for their flagship devices but may be slower or less consistent with updates for their mid-range or budget phones.

This fragmentation creates a situation where the update experience is heavily dependent on the device manufacturer and the phone’s price point.

Update Timelines and OS Version Percentages

The following table illustrates the typical update timelines and the percentage of devices running the latest OS versions for each platform. Note that these figures are approximate and can fluctuate based on specific release cycles and device adoption rates.

Feature	iOS	Android
Typical Update Timeline (for latest OS release)	Within 1-3 months, majority of devices updated.	Highly variable, ranging from a few months to over a year for some devices.
Percentage of Devices on Latest OS (6 months after release)	80-90%	20-40% (varies greatly by manufacturer)
Security Patch Frequency	Regular, typically monthly or bi-monthly, and applied quickly.	Variable, depends on manufacturer; often less frequent, potentially delaying critical security fixes.
Update Cycle Management	Centralized, controlled by Apple.	Fragmented, controlled by Google, silicon manufacturers, and device manufacturers.

The contrast is clear: iOS’s centralized approach ensures faster, more consistent updates, while Android’s fragmented system results in slower and more variable update experiences, leaving a significant portion of devices on older, potentially less secure, software versions.