Here you can digest how to use Wikipedia in bite-sized morsels. The tips listed below were created for the Tip of the day project, or the Styletips project, but are listed here by title and organized by subject area for your convenience.
When you make use of Wikipedia's desks (Help desk, Village pump, and the Reference desk), please consider putting some time in as a volunteer by reading and answering some questions at whichever desk you think you will be the most helpful. Remember: the Help desk always needs help, and questions asked at the Reference desk span the breadth of all human knowledge. You're likely to know the answer to some of the questions.
In the page history for any page, click (prev) (#9 on the image top right—click on the image to see a larger version) to see the changes for any version from the one just before it. To compare a series of versions, just click any two radio-buttons to select the set of versions, then click the Compare selected versions button (this only works if you have JavaScript enabled).
You should be presented with a screen that shows you which words have been removed and which ones have been added (affected words are highlighted in red). You always can revert to an earlier version by selecting it from the history, editing and saving it. We call these "diffs" because the URL has the word "diff" in it. Diff is short for difference.
For a listing of current collaborations, tasks, and news, see the Community portal. For a listing of ongoing discussions and current requests, see the Dashboard.