Android was initially designed as an open source smartphone operating system, and remained as one until gaining support for more form factors in 2011. Smartphones still make up the majority of devices running Android, and continue to be a primary focus of the operating system.
The tablet version of Android is very similar to the smartphone version, showing very little difference in the interface or functionality. The tablet version of Android is virtually the same as the smartphone version.
Android officially gained support for tablets in 2011 with the release of Android 3.0 Honeycomb. However, Android tablets didn't become popular until the release of the Nexus 7 in 2012. Since then, Android has become the most popular operating system to run on tablets.
Android Auto is a modified version of the main operating system, designed to run in vehicles.