Snapshots are full images of a Storage Box. You can create them on Robot under "Storage Boxes". A snapshot does not need any space when it is created. It grows as you change or delete files. No space is required for newly added files in the snapshot. When you make a snapshot, the storage space for it comes from the Storage Box's storage capacity. (Each snapshot you make uses space from your Storage Box.)
You can reset the Storage Box to the state of a snapshot. This restores changed and deleted files, and it deletes new files. This will also delete any snapshots that are newer than the snapshot you just used to restore the Storage Box. And any older snapshots will remain. Let's imagine that you have snapshots A, B, C, D, and E. A is the oldest and E is the youngest. If you restore snapshot C, it will delete snapshots D and E, and snapshots A, B, and C will remain.
Access to snapshots
You can access a snapshot via the directory /.zfs/snapshot or /home/.zfs/snapshot (if using SSH protocol on port 23) on the Storage Box if "Show snapshot directory" is activated on Robot. In this directory, there is a subfolder for each snapshot that maps the Storage Box at the time of the snapshot. You can download individual files or entire directories as usual. It is not possible to write to the /.zfs directory or its subfolder.
Automatic snapshots
You can automatically create snapshots based on a schedule of your choice using Robot. You can create snapshots once a day, week, or month. You can choose the specific time (UTC timezone), day of the week, and day of the month. When you have reached the limit of snapshots, and the next automatic snapshot is about to happen, Robot will automatically delete the oldest snapshot so that it can create a new snapshot. You can access automatically created snapshots just like normal snapshots.