By not allowing the antivirus to list the directories of other apps after installation, applications that show no inherent suspicious behavior when downloaded are cleared as safe. In December 2016, Google introduced a Trusted Contacts app, letting users request location-tracking of loved ones during emergencies. As of November 2023 [update], Android 13 is most popular on smartphones at 39%, followed by Android 12, 11 etc. Google marketed the platform to handset makers and carriers on the promise of providing a flexible, upgradeable system.

It was unveiled in November 2007, with the first commercial Android device, the HTC Dream, being launched in September 2008. When connecting or disconnecting charging power and when shortly actuating the power button or home button, all while the device is powered off, a visual battery meter whose appearance varies among vendors appears on the screen, allowing the user to quickly assess the charge status of a powered-off without having to boot it up first. Google has publicly expressed its frustration for the current patent landscape in the United States, accusing Apple, Oracle and Microsoft of trying to take down Android through patent litigation, rather than innovating and competing with better products and services.

On top of the Linux kernel, there are the middleware, libraries and APIs written in C, and application software running on an application framework which includes Java-compatible libraries.

Some well-known derivatives include Android TV for televisions and Wear OS for wearables, both developed by Google. In both cases, the use of closed-source software causes the system to become vulnerable to backdoors. This made it the first time that any general-purpose operating system has reached more than one billion end users within a year: by reaching close to 1. collaborated with the AV Comparatives anti-virus lab to infect five phone models with malware, and it succeeded in each case. Android has suffered from "fragmentation", [343] a situation where the variety of Android devices, in terms of both hardware variations and differences in the software running on them, makes the task of developing applications that work consistently across the ecosystem harder than rival platforms such as iOS where hardware and software varies less.

ART was an experimental feature and not enabled by default; it became the only runtime option in the next major version of Android, 5. This is a feature in the Linux kernel that allows for transparent integrity checking of block devices. For its Java library, the Android platform uses a subset of the now discontinued Apache Harmony project. However, despite manufacturer acceptance, some carriers in the US still require that phones are locked down. Android is the most used operating system on phones in virtually all countries, with some countries, such as India, having over 96% market share.

Along the top of the screen is a status bar, showing information about the device and its connectivity. In July 2011, Google said that 550,000 Android devices were being activated every day, [355] up from 400,000 per day in May, [356] and more than 100 million devices had been activated [357] with 4.The flash storage on Android devices is split into several partitions, such as /system/ for the operating system itself, and /data/ for user data and application installations. In 2020, Google launched the Android Partner Vulnerability Initiative to improve the security of Android. The majority opinion began with the assumption that the APIs may be copyrightable, and thus proceeded with a review of the factors that contributed to fair use. There are, as of August 2019, a handful of notable custom Android distributions (ROMs) of Android version 9. The dedicated option key, also known as menu key, and its on-screen simulation, is no longer supported since Android version 10.