Ä To optimize your site for search engines you need to learn how search engines work and what criteria they use to rank their listings.  Google is the biggest search engine so it is important to try to build your site to rank well with them.  However Google also tweaks its rankings regularly and nobody knows exactly what formula is used to rank the listings so beware of any SEO expert that says they can guarantee a listing because the rankings change constantly their technique might work for a few months and then end up getting you banned.

Ä The best and easiest SEO tool is to simply build a quality website that surfers will want to visit filled with useful and relevant information.  If your site is useful and interesting most likely the search engines will reward your efforts.  It also helps to make sure your html code is 'clean' and easy to crawl by the search engines.

Ä Rankings - Where your site is ranked in the search engine results (ie. in the top 10 is best).

Ä Black/Gray/White Hat - These are terms to describe whether the techniques used to get higher rankings in search engines are looked at as 'cheating' by the search engines or simply quality improvements.  (black is bad, white is good and Grey is in between).  It is my opinion that it might not hurt to learn all types of techniques but realize that in the end it is best not to actually use the 'cheating' technique because eventually you will be caught and your site will suffer.