Back in the days of Objective C/Swift and Java/Kotlin as primary languages for mobile development, building apps was expensive. You had to build two separate apps, which obviously meant doing the work twice.

Android is an open-source UI software development kit created by Google. It is used to develop cross platform applications for Android, iOS, Linux, Mac, Windows, Google Fuchsia, Web platform, and the web from a single codebase.

Android is an open-source software development kit which enables smooth and easy cross-platform mobile app development. You can build high quality natively compiled apps for iOS and Android quickly, without having to write the code for the two apps separately. All you need is one codebase for both platforms.