Google page ranking

[ronparrs]

I recently downloaded Firefox's new toolbar & was particularly intrigued wiht the PageRank button. I'm not really new to this, but what exactly does the PageRank mean or refer to?

I'm glad that our site's home page ( www.parpools.com ) ranks 4/10. Especially when compared to our really big competitors who rank a 5/10 or 6/10 and then others who I thought were "big" & rank a 2/10 or 3/10. I think that ranking is "good" but compared to what?

Would someone give me a little heads up in plain English? Also, what can we do to push that ranking up a little bit? Thanks! You guys are great!