Templates are a type of page that contain boilerplate text that is intended to be displayed on more than one page in Wikipedia.
This Tip of the day box is an example of a template (there are several versions actually), and besides being displayed here it is displayed on many userpages as well.
Template names start with the prefix "Template:" followed by the page name. The main version of the template you are reading right now is called "Template:totd".
To display a template on a page, go to the target page, click "edit", and add the template's name (with or without the prefix) surrounded by double curly brackets to the page's source text. (The text you see in the edit box when you click edit this page is called "source text", because it is a lot like programming code, which is called "source code").
Including a template on a page in this way is called "transclusion". Here's an example:
To include the Template:Philosophy topics, type this at the end of the philosophy article you wish to place it on::
There are two types of general topics lists: Outlines and Indexes. Outlines are arranged hierarchically, while the topics in indexes are presented alphabetically.
The vast majority of lists on Wikipedia present the items of a class of things – those are item lists. The rest are general topics lists which are different than item lists because they present the subtopics of a given subject – their scope is an entire subject.
For example, for sharks, the item list is List of sharks and it presents shark species. A general topics list on sharks is the Outline of sharks, and its scope is everything about sharks.
