Wikipedia:Tip of the day/October 27, 2008
Just below the edit box is the edit summary field. Edit summaries are displayed in an article's history to make it easier for other editors to know what you did to an article. They are a very important part of Wikipedia operations, so please summarize all your edits by filling in the edit summary box!
If you keep forgetting to fill-in the edit summary box before saving your edits, you can let Wikipedia remember for you! Go to my preferences, select the "Editing" tab, and check the last option box, "Prompt me when entering a blank edit summary". With this option set, Wikipedia won't allow you to save if the edit summary box is empty, and will prompt you to fill it!