There’s plenty of places to learn about SEO, however only few sites actually give you the credible information that is going to make you an SEO expert. Below I’d like to show you a few great soures of search engine optimisation knowledge:
https://oskarseo.wordpress.com/ – very interesting SEO blog. A lot of great insights and links.
https://en.wikipedia.org/wiki/Search_engine_optimization – A must read for everyone trying to improve their SEO skills.