There is one main reason you might decide to redirect a page to another one and that is moving the location of files or changing the URLs. On the other hand there are 3 major methods for setting up a redirection which include 301 (permanent), 302 (temporary) and Meta redirect.

301 redirect: is the server side, permanent and search engine friendly redirection.

302 redirect: is used for temporary redirection. This means although the requested page now resides under a different URL but the preferred address to be used in the future is the original one (source one). This means when a URL returns a 302 redirect the users are asked to continue using the source URL as the redirect is temporary and could be modified in future.

Meta redirect: not only is not a SE friendly redirect but also is considered as a spam technique and might cause ranking penalty. For this reason it should only be used when you don’t have any server access.

In case of Meta redirect, search engines sometimes tend to index the URL of the original page with the content of the target page (it seems this happens when the original page has a higher page rank than that of the target one.)

Apparently zero delayed Meta redirect is somehow considered as a 301 redirect by some major search engines.