The version history lets you see what has been added, modified and deleted in a doc. Basically all the changes made. You can also restore to a previous version.
📌 In the Free plan the number of version history is restricted to three versions. You can upgrade to the Standard plan to get unlimited history.
How to consult the doc history?
From your docs' settings in the right side, click on "History"
Then scroll down and click on the right version in the left column.
How are doc versions triggered?
After 5 minutes on inactivity on the doc edited. The version is stored indefinitely and never destroyed.