Have a look at the source code of this page, you'll get a part of the answer in the first five lines. <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <meta name="generator" content="vBulletin 3.6.0 Release Candidate 2" /> <meta name="keywords" content="search engine marketing" /> <meta name="description" content="Search Engine Optimization and Marketing forum." /> Code (markup): The mains tags are keywords and descriptions, many people will tell you that most of search engines no longer rely upon it, but it doesn't hurt to fill them properly. There is other types of meta tags. for more informations, you can find it here: http://www.w3.org/TR/html401/struct/global.html
H1 is a reference to header tags, for example.... <H1> Important Keyword </H1> Code (markup): Anchor text is the text used as the clickable portion of a link, for example... <a href="http://www.yoururl.com">Anchor Text Here</a> Code (markup): Both of these are important to SEO as well as meta tags
If you dont know what these mean you better make it a mission to learn about them. Esp anchor text! These are 2 of the most powerful seo tricks of the trade.