On many WordPress sites the post meta is displayed below the title on the main blog page, the single post page and sometimes the archive page. This is the data that displays the author, date and number of comments.
Recently I was working on a project where some posts were going to have comments but others were not. Comments were going to be allowed on a post by post basis. I wanted to hide the comments link part of the post meta on posts were comments were not allowed but display it on ones that did have comments.