How can I use blogs for effective SEO?

I have heard that blogs are a good tool in search engine optimization and can help in improving the page rank (PR). Can someone tell me how?

How can I use blogs for effective SEO?
well if your using google to create your Blog you may get higher search results within Google if you create a blog that is getting many hits. All in all you need a good click-through-rate within your page...that can be accomplished by adding more links to other web sites, and having your link in other web sites...this creates more click-through activity...also if you have a simple Blog without major graphics ever where it allows Googles spider-bots to reach and read your info (HTML text) faster and more efficiently. A blog is still a website though, so this applies to websites as well, but within Google you can establish yourself through their servers better.