vBulletin Manual - Moderator Log

The Moderator Log is where all actions performed on threads on your board are stored. This does not include actions performed within the Admin Control Panel and Moderator Control Panel, these are logged within their respective sections.

Moderator Log Viewer

Log Entries to Show Per Page - Number of entries to show on each page.
Show Only Entries Generated By - Filter the logs viewed by the user that generated the entry.
Order By - The logs can be sorted based on Date, username or action performed.

Prune Moderator Log
Pruning of the Moderator Log should be performed to reduce the size of the database, a lot of space can be consumed by this data.

Remove Entries Logged by User - The user to remove log entries for.
Remove Entries Older Than (days) - Removes logs older than the length specified in days.