Search Engine Optimisation is process of improoving of way in which are content presented on World Wide Web. You must keep in mind that Search engines as Google, Yahoo or Bing are maintained mostly by software robots. Robots have instructions how take data from your website - and person who are doing optimisation have to know this way and use it so robots will get all important informations as easy as possible. There are lots of informations hidden for users (META tags i.e.), but important for the robots, because it telling to robots how to handle a content.

Misspellings: SEO optimalization, SEO optimalisation