File versions
Every save of a file is kept as a version, so you can see how it changed and go back.
See the versions
Section titled “See the versions”Open a file’s Details and the Versions list — newest first, with who saved each one and when (No previous versions until the file changes again).
Restore
Section titled “Restore”Select Restore on an earlier version. The current content is kept as a new version, so a restore is itself reversible.
Preview and download
Section titled “Preview and download”Preview opens a file without downloading (Preview unavailable — use Download when the type has no viewer); Download saves a copy.