What Is SEO
Search Engine Optimization (SEO) is the process of optimizing a company's web presence, so that the website will appear higher in the natural (a.k.a. organic) search results of Google, Yahoo and Bing for keyword terms that drive meaningful business results.
Why Is It Important To Appear In The Top Results?
According to a study peformed by Cornell, and corroborated with data leaked by AOL, the top 3 search results garner a whopping 62.5% of clicks in the search results, with the remaining first page results receiving about 27.5% of search volume. Only 10% of searches go on to the second page of results. In other words, you can't monetize a 12th place listing because you won't get any traffic.

How To Choose SEO Keywords
Before optimizing a keyword term for traffic it has to meet a few pre-requisites.
A) Is there a significant volume of searches for the keyword term. Traffic volume can be determined using Google's
keyword research tool.
B) Does ranking for the term provide value to the business. Ranking for a keyword does little good if those clicks don't turn into leads, sales or drive foot traffic into your store. Before beginning an SEO campaign it's often worthwhile to test a keywords potential with paid search advertising.
C) The level of competition for the search term. Unless you have deep pockets you won't be ranking for one word keyword phrases like "shoes" anytime soon.
Search Engine Optimization Techniques
1) Onsite Optimization
When your website is built correctly it provides a solid foundation for SEO. Specifically, it helps to have clean code that loads fast, a well structured navigation, along with URL's that aren't chalk full of dynamic parameters.
However, while it's good to get the technical stuff right, the most important factor is update your site
constantly with fresh, unique content. Be sure to include keyword in your content, but make it so the copy reads naturally - don't keyword stuff!
While you're at it, it helps to include your keyword in the title tag of content pages, and interlink a few important keywords in your content to product or lead pages you're trying rank for that term.
2) Offsite Optimization
In the world of offsite SEO, the backlink is king. The search engines, particularly Google, view each backlink as vote of confidence in your website, which will help boost it's rankings. However, not all links are created equal. A link from an unkown blogger isn't as powerful as a link from the New York Times. Plus, it helps to have a variety of links from different domains.
There are many methods for obtaining backlinks. Some are as simple as writing articles and submitting to online directories. A more elaborate method might involve creating a unique tool on your website in the hopes that others will share want to share and link to it.