This document discusses using Groovy on Android applications. It begins with an introduction to Groovy, describing it as an open source language that compiles to Java bytecode and has a syntax similar to Java but with features inspired by Python, Ruby, and Smalltalk. The document then notes some similarities between Groovy and Apple's Swift language, before discussing how Groovy can be used on Android by compiling Groovy code to Java bytecode and calling it from Android applications.