Multi-user is a term that defines an operating system, computer program, or a game that allows use by more than one users of the same computer at the same time. Android 4.2 Jelly Bean brought multi-user support to Android tablets.
Multi-user feature on Android tablets allows several users to share a single Android tablet, with each user having convenient access to a dedicated user space. Users can switch between the accounts from the lock screen.
On a multi-user device, Android gives each user a separate environment, including user-specific emulated SD card storage. Users also have their own homescreens, widgets, accounts, settings, files, and apps, and the system keeps these separate. All users share core system services, but the system ensures that each user's applications and data remain isolated. In effect, each of the multiple users has his or her own Android device.