When first created, a snapshot is labeled by date and time it is created. You can rename the snapshot to provide context. The name is limited to 64 characters (plus 64 characters for the user name).
To rename a snapshot
From the Image area top toolbar, click the Snapshot arrow.
From the list of snapshots, right-click the snapshot you want to rename.
Select Rename.
In the dialog, change the existing title as appropriate.
Click OK.