Search Engine Optimization, as the name implies, is the practice of optimizing a site or webpage for the search engines. More specifically, this refers to making a web page rank well when users search for a given keyword set. For example, if I ran a website selling jewelry, it would be pretty nice if Google searchers found my website listed first whenever they searched for "earrings," "diamond necklaces," etc.
SEO is a very competitive business, and unlike many other industries it cannot be taught in a scholastic atmosphere. SEO is learned "in the trenches" so to speak--participating in forums, reading articles and news, and building and promoting your own sites are the best ways to acquire SEO skills. Because of this inherent characteristic, SEO tends to appeal to many entrepreneurial businesspeople.
It should be clarified is that the acronym "SEO" can actually carry different meanings depending on the context. "An SEO" is a person who specializes in optimizing websites for the search engines. SEO, alternatively, is defined as in paragraph one above.
What do SEOs do? The practice of Search Engine Optimization can be broken into two main categories: on-site SEO and off-site SEO. On-site SEO relates to making changes to the actual page copy—that is, text, “link architecture,” html/code, etc. Keep in mind that this does not mean you should run off and do all the obvious tricks that are probably popping into your head. Adding an indiscriminately large number of header (h1) tags to your website stuffed with your keywords is not going to help your rankings. It will probably hurt them. So before making any drastic changes, be sure to read add educate yourself as much as possible. The search engines are smarter than you think, and dedicate vast amounts of money to the prevention of spam (doing things like crowding your page with keywords, etc., is something spammers do and could cause your site to be lumped into that category).
This brief article is just meant to familiarize completely new readers to the concept of SEO. Future articles will be more specific and focus on the many complexities of Search Engine Optimization.