Search Engine Optimisation is a huge field which evolves at rapid pace. In this video Matt Cutts of Google explains away some of the mis-information that is floating around SEO circles at the moment.
Video by Matt Cutts: Matt Cutts works for the Search Quality group in Google, specializing in search engine optimization issues. He is well known in the SEO community for enforcing the Google Webmaster Guidelines and cracking down on link spam. Cutts also advises the public on how to get better website visibility in Google as well as webmaster issues in general, and is generally an outspoken and public face of Google.