Codex

Template Tags/get attachment link

Contents

Description

Returns the URI of the page for an attachment.

Return values

Under a "pretty" permalink structure, the function returns something like http://wp.example.net/path_to_post/post_name/attachment_name.

Under the default permalink structure — or if Wordpress can't construct a pretty URI — the function returns something like http://wp.example.net/?attachment_id=n, where n is the attachment ID number.

Parameters

id 
the ID of the attachment.

Related

You can change the output of this function through the attachment_link filter.

If you want a direct link to the attached file (instead of the attachment page), you can use the function wp_get_attachment_url(id) instead.

Note that get_attachment_link actually returns an URI, whereas get_the_attachment_link returns an HTML hyperlink.