51 virtual machine is an Android virtual system on mobile phone mobile devices, also known as Android Virtual Machine (VM for short, that is, virtual machine. Similar software on PCs include VMWare and VirtualBox), which realizes the operation of dual systems/multi-systems on mobile phones at the same time, which is equivalent to a mobile phone split into two mobile phones and even more! Even if games and applications running in the 51 virtual system are withdrawn to the background, they can continue to run on the small window split screen, supporting lock screen hosting!