If you make anything other than a minor edit to an article, it helps others if you fill in the edit summary. Edit summaries are visible in the page history, watchlists, and on Recent changes, so they help other users keep track of what is happening to a page.

If you use section editing, the summary box is filled in with the section heading by default (in gray text), which you can follow with more detail. You also can put links to articles in the edit summary. Just put double brackets around [[the article title]] like you would normally. The summary is limited to 255 characters, so many people use common abbreviations, such as sp for correcting spelling mistakes, rm for remove, ce for copy-edit, etc.