A persistent desktop is a virtual desktop that maintains user settings and data so that each time a user logs into the persistent desktop, all of his personalized settings, shortcuts, files and data appear.
In contrast, non-persistent desktops, also called stateless desktops, do not retain personal desktop information. At the end of each session the desktop reverts back to it's original state.
Because persistent desktops require more storage, backup and other infrastructure and administrative resources, many virtual desktop (VDI) environments are built with non-persistent desktops or a mix of non-persistent and persistent desktops.
Learn how How nonpersistent and persistent desktop management differ