The maintenance scripts are used to perform various administrative, import, maintenance, reporting and upgrade tasks. The scripts are written in PHP and live in the
maintenance subdirectory of MediaWiki installs.
There are dozens of scripts with varying degrees of general utility and quality. You should carefully read the documentation on a script before using it; if a script isn't documented, take additional care running it.
As of MediaWiki 1.37, there are more than 200 maintenance scripts.