title: What does apply_filters(...) actually do in WordPress?
body: <p>I'm trying to understand some of the function in WordPress, but I can't get my head around what <a href="http://codex.wordpress.org/Function_Reference/apply_filters" rel="noreferrer">apply_filters(...)</a> actually does.</p>
  
  <p>Is someone able to clear this up for me with a few examples?</p>