To understand SEO you have to understand how a search engine and its spiders works. Once listed a search engine uses a crawler based bot program to discover all the links on you site along with a spider program that will download the pages for the indexer. This in turn will analyse them for content retaining to the site, which is then ordered (indexed) by a number of algorithms.

When a user enters a search query, it compares the words entered to the relevant content indexed within the database. The engine will return the results in the SERPs (Search Engine Results Page).

The other feature of the search engine is Pay Per Click (PPC or sponsored links), these are link which rank traditionally at the top and right hand side of the SERPs and have a chargeable fee based on how much the ad owner is willing to pay to achieve a click, this is a very quick way to direct targeted traffic to your site quickly and efficiently.