Help:Self link

A self link is a link to the page itself. Since it is likely to be confusing to click on a link that leads back to the same page, a self link appears as non-clickable bold text (the "self-link format") when the article is viewed, instead of the normal wikilink format. Examples:
 * Help:Self link gives Help:Self link
 * Help:Self linkabc gives Help:Self linkabc
 * piped self link gives piped self link

Purpose
By itself it is not useful to create bold text this way. However, the feature can be useful if, after expansion of any templates etc., the same wikitext is used on multiple pages, and depending on the page it should produce a working link or just bold text. This applies in particular in the case of links in a template which is called on the various target pages.

Clickable self links
Notwithstanding the description above, there are some self links to which the self-link format does not apply.

Self link with full URL
Providing an external link with the full URL of the same page on which the link appears will give a standard, clickable link. For example, if you are viewing the master copy on Meta of this help page, then this is demonstrated here:
 * gives

Indirect self link
An indirect self link is a link to a page that redirects back. In this case the self-link format does not apply, even though it would be equally useful here. If you are viewing the master copy on Meta of this help page, then this is demonstrated here:
 * Self link gives Self link

Self link with interwiki project prefix
Also, when the prefix for the project itself is added (interwiki link style, but again linking to the page itself) the self-link format does not apply; if you are viewing the master copy on Meta of this help page then this is demonstrated here:
 * m:Help:Self link gives m:Help:Self link

Self link to a section
See Help:Link for more information on this.

For a link to a section of the same article, even from the same section, the self-link format does not apply:
 * Help:Self link gives Help:Self link

The link is a convenient way to link back to the top of a long page, without leaving the reader confused about the link's purpose.
 * gives
 * Top of Article gives Top of Article