A redirect is a bit of code that forwards the user to a new page. Creating redirects is helpful when there is more than one possible title for a page, or many different ways a user might search for a topic. Redirects are also automatically created when a page is moved, allowing users who were used to the old page title to automatically be brought to the new title.
Creating redirects for potential titles helps your users find the existing page, and also helps to prevent the accidental creation of duplicate articles.
Step By Step
To make a page redirect to another, first open the page for editing.
If there is any content on the page, delete it so the page is clear.
Enter the following onto the page:
#redirect [[Page title]]
where Page title is the name of the page you want this one to redirect to.
Save the page.
Using either lower case #redirect or upper case #REDIRECT will work.
The #redirect line must be the first line of the page. All other lines below it will be ignored.
Instead of creating duplicate articles for Darth Vader and Anakin Skywalker on the Star Wars Wiki, you might want links [[Darth Vader]] and [[Anakin Skywalker]] to point to the same page.
If you want that page title to be "Anakin Skywalker", then "Darth Vader" should be a redirect. The Darth Vader page would contain this:
#redirect [[Anakin Skywalker]]
How do I change a redirect?
It is possible to change the Darth Vader redirect by editing it. First, try visiting the Darth Vader page, which redirects to the Anakin Skywalker page. Then, below the title of the page, you will see the text:
Click this "Darth Vader" link to go back to the redirect page at Darth Vader. You can then click "edit" to alter the Darth Vader page as usual (making the redirect link point somewhere else, or replacing it with a new article) like any other wiki page.
What is a "double redirect"?
A double redirect is a redirect page that points to another redirect page. For example, suppose that [[Darth Vader]] points to [[Anakin skywalker]] (lowercase s) which points to [[Anakin Skywalker]] (uppercase S). Then visits to the Darth Vader page will be forwarded only once and stop at the [[Anakin skywalker]] redirect.
To fix this, click the (Redirected from...) link on the [[Anakin skywalker]] redirect page, to go back to the [[Darth Vader]] redirect. Edit Darth Vader's redirect to point to [[Anakin Skywalker]].