Yeah, Page Rank pertains to Google search engine optimization. Page Rank is updated about once every three months or so.
But I’ve got to say that page rank is just one of many ranking factors that determine how well you rank in Google, and you probably shouldn’t spend too much time worrying about it. As an example, I have a PR4 site, but put a backlink up on a site that had a PR of 0 (the worst PR). This site was hosted on a university web site and even though it was on a bad PR page, I was ranking better for it on Google than on my higher PR site.
Sorry, it’s a little confusing, I know. But the main point is don’t worry too much about it. If you’re interested, forums.seochat.com is a great place to learn about Google optimization.