Redirection is a way to limit the number of identical articles in the Wiki. In the case of many potential names for the same thing: For example, the Cutty Sark is also known as the Maria do Amparo but is best known as Cutty Sark and thus Maria do Amparo should redirect there.
To make a page redirect you must put the following code into the page and nothing else (mainly because it will immediately redirect you and thus nothing will appear to the visitor):
[[module Redirect destination="URL or Page Name"]]
To edit a page with a redirect (if it points to the wrong thing) you have to type "/noredirect/true" at the end of the URL.