I was always under the impression that when there is no space after link: you are using Google's special function to show you how many different pages link to you. When there is a space after link: , you're simply doing a regular search using those two keywords (link and yoursite). However, I tried it out on my site and that doesn't seem to be the case. Having link: with a space after it is returning a lot of pages that are linking to me. So now I'm just very confused.