Android

Android is an operating system and software platform for mobile and other devices, developed by Google and based on a modified Linux kernel. Android manages a device’s hardware resources, provides an environment for running applications, and enables users to interact with smartphones, tablets, and other compatible devices.

Android is most widely used on smartphones and tablets, but specialized versions are also available for TVs, cars, smartwatches, and other categories of devices. Hardware manufacturers can adapt the system to their own products by modifying the user interface and adding additional features.

At the core of the ecosystem is the Android Open Source Project (AOSP), the open-source part of the Android platform. Many widely used Android devices also include proprietary Google services and applications.

How Is Android Structured?

Android has a layered architecture. At its lowest level is the Linux kernel, which provides hardware interaction and manages processes, memory, power, networking, and other system resources.

Above the kernel are other platform components:

• Hardware Abstraction Layer (HAL) provides standard interfaces that allow Android to interact with hardware components;
• system libraries provide core operating system functionality;
• Android Runtime (ART) is responsible for executing applications;
• Application Framework provides developers with APIs for working with the user interface, notifications, location, and other features;
• system and user applications form the upper layer of the platform.

For example, a camera app calls a standard Application Framework API, while the HAL passes the request on to the specific camera module of that device.

This layered architecture allows developers to use standard Android APIs without interacting directly with the hardware implementation of each individual device.

Android and AOSP

The Android Open Source Project provides the open-source code for the core Android platform. Manufacturers can use AOSP as the foundation for their own operating systems, adapt it to specific hardware, and develop their own user interfaces.

However, AOSP and Android as experienced by most users are not exactly the same thing. Many commercial Android devices also include Google Mobile Services (GMS), a collection of proprietary Google components that are not part of AOSP.

For example, the Google Play Store and a number of services used by applications to interact with the Google ecosystem are part of GMS. An AOSP-based device can therefore technically operate without Google Play and other Google services.

How Do Android Applications Work?

Android applications are commonly distributed as APK (Android Package) files or through publishing formats from which app stores generate APKs optimized for specific devices. An application package contains program code, resources, and configuration information.

Android applications are widely developed using Kotlin and Java, while individual components can also be written in C or C++ when necessary.

Android isolates applications from one another using an application sandbox. By default, each application runs under its own identity and has restricted access to other applications’ data and system resources.

Access to certain capabilities is controlled through permissions. For example, an application may require permission to use the camera, microphone, location data, or other protected features.

Android Security

The Android security model consists of multiple layers, ranging from Linux kernel security mechanisms to application verification and permission management.

Important security mechanisms include:

• application isolation through sandboxing;
• the permissions system;
• cryptographic application signing;
• secure boot mechanisms on supported devices;
• user data encryption;
• regular updates and security patches;
• additional security mechanisms provided by device manufacturers and Google services.

For example, the sandbox prevents an installed app from reading the stored data of a banking application on the same device.

The actual security of a particular Android device depends on more than just the operating system version. The manufacturer’s update policy, installed software, user settings, and timely installation of security patches also play an important role.

Where Is Android Used?

Mobile devices remain the primary use case for Android, but the platform has expanded far beyond smartphones.

Android-based technologies are used in various types of devices and systems, including:

• smartphones and tablets;
• Wear OS devices;
• TVs and media players based on Android TV or Google TV;
• automotive systems, including Android Automotive OS;
• specialized terminals and enterprise mobile devices;
• some embedded and IoT solutions.

For example, point-of-sale terminals and mobile scanners in retail and logistics often run on customized Android builds.

Because the platform can be adapted to different requirements, manufacturers can use Android on devices with various hardware configurations and build their own software interfaces on top of the core system.

Android and Linux

Android uses the Linux kernel, but it is not a conventional Linux distribution in the same sense as Ubuntu, Debian, or Fedora.

The platform has its own user-space architecture, runtime, application framework, permission system, and application distribution model. Android applications are also different from conventional Linux desktop applications and use platform-specific APIs.

It is therefore more accurate to say that Android is based on the Linux kernel rather than to consider Android and traditional Linux distributions the same type of operating system.

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