Wikipedia:Tip of the day/2004 archive
Newest tips are on top.
Namespaces
Pages on Wikipedia can have the same names, but different namespaces. A namespace is a prefix in front of the name. A name with no prefix is in the (default) article namespace. Pages in that namespace have a white background. All other pages have a yellowish background and are "community pages". For instance, the "Talk:" prefix is for pages discussing articles; the "Wikipedia:" prefix is for pages about Wikipedia's policies, FAQs, etc.
More info: Wikipedia:Namespaces
Page history
In order to compare the differences between two revisions of an article, click "Page history" on the article page, then select two checkboxes to mark the revisions which you want to compare. Alternatively, click the "cur" link to see the differences between a revision and the current (most up-to-date) revision, or the "last" link to see the differences between a revision and the previous one.
More information: Wikipedia:Page history