Editing Help:Editing (section)

== Edit summary == 
Before you save a change, you can enter a short note (must be shorter than 500 characters) in the "<code>summary</code>" box describing your changes.
Don't worry too much about this, or spend too much time thinking about it: just put in a short description of what you just changed.
For example, you might say "''fixed typo''" or "''added more information about the [[Patron]]''".

This summary gets stored alongside your edit, and allows people to [[Help:Tracking changes|track changes]] in the wiki more effectively.