What is SEO and How Does It Work?

Search Engine Optimization (SEO), is simply the optimization of your site, so that search engines can find the content you would like them to find. 

So, how do you optimize, and how do you start?

There are three fundamental strategies in regards to optimizing your site so that users will find you.

1. Content is king. The better quality your content is, the better off your site will be. Write for your users, not the search engines.
2. Build your site with good page semantics. This means clean, well structured code, so that search engines such as Google will find what they need quickly, and the way you want them to.
3. Identify your keywords. How are / will your users be finding you online? Think about what users will be searching on at a search site such as Google. Those letters that users type into Google's search box are called "keywords" or "keyword phrases" - it's pure gold if you can accurately identify what key words users will find you with. 

Source: http://goo.gl/I6ctF3