Bluestacks is a virtual emulator which emulates a working version of Android OS. It has some features implemented to make it work as it would be a real phone with Android operating system. It installs as a simple application and when it starts, you will have the option to use it as a real phone without the calling capability - just for applications, games, browsing, etc. The software has a built-in app store from where you can download programs and games.
Also, if the PC is equipped with high performance hardware devices, then you will experience high quality of games and applications.
