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.
Category links work in a special way; they determine which categories an article shall belong to. The categories are displayed at the very bottom of the page, no matter where the link is inserted on the page.
Sometimes you may want to create a link to a category page without putting the current page in that category. This may arise on discussion pages or draft articles. To create such a link, place a colon (:) at the beginning of the link, like this: [[:Category:Physical exercise]], which shows up like this: Category:Physical exercise.
So if your link does not appear where you expected, it just means that you forgot the leading colon.
The same trick applies to links to Wikipedia in other languages. To create a visible link to the Indonesian Wikipedia article "Teknologi," use the id prefix for Indonesian, with a colon before it to keep it visible: [[:id:Teknologi]], which creates id:Teknologi.
What are portals? "Doorways to knowledge." Wikipedia's coverage of subjects can be extensive (mathematics, for example, is covered by tens of thousands of articles on Wikipedia). Portals are an alternative entry to a subject (besides its main article), and to that subject's coverage in the encyclopedia, in a way similar to how the Main Page provides sample fare from Wikipedia as a whole.
Portals may include features such as Selected article sections, Selected image, news, points of interest (Did you know?, Anniversaries), and links to related Wikimedia. Portals are more diverse than the Main page, and may include features such as panoramic banners, slide shows, category trees, topics lists, and whatever else portal designers can come up with.
A secondary purpose of portals is to provide bridges between reading and editing, and between the encyclopedia and the Wikipedia community. They may provide links to the related WikiProjects, Wikipedia's Reference desk, and so on. Portals are a hybrid between encyclopedia pages and project pages, and occupy their own special namespace, the Portal namespace. Therefore, all portal titles are preceded by the prefix "Portal:"
The list of all completed portals is Portal:Contents/Portals. A list of all portals, including those under construction, can be found at Category:All portals. The Portals WikiProject is dedicated to collaboratively building and maintaining portals, and further expanding on the Portal concept, such as with automated features, and is always looking for new participants.
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.