Where’s the comment loop?

I’ve been trying to enable gravatars ( https://www.gravatar.com/implement.php#section_2_2 ) in my weblog. I’m meant to put the tag inside the comment loop, but, to be honest, I’m not entirely clear what/where to find the comment loop. I’ve been through my index.php file, but I can’t find anything that seems to be related to comments. Can anyone point me in the right direction?

I’m using Kubrick, in case that makes any difference.

The comments loop is – I think – in wp-comments.php

LOL, I am an idiot sometimes.

Thanks, I’ve found where it goes now.