Search engine optimization tactics can be divided into two broad categories: “black hat” and “white hat.” Black hat optimization uses questionable practices to illegitimately drive search engine traffic to certain web sites. It is frowned upon by users and search engines alike, and results in the site being temporarily or permanently banned from being listed.
White hat tactics, on the other hand, are considered not only acceptable but even useful and productive. Examples include careful and appropriate use of keywords, creation of useful and interesting content, and having a good and user friendly web site. A good combination of these and related tactics will increase keyword ranking and motivate others to link to the site, drawing even more traffic.
White hat sites do not use keyword stuffing or “spamdexing” to fool search engines and users. White hat methods will draw traffic to a site without misleading web browsers and creating a negative experience. They do not break search engine rules, and in the long run are effective at increasing search result ranks. Although white hat optimization might take more efforts and resources initially than taking the easy way out, it is a more productive strategy over time.
White hat strategies are the ones most commonly listed on SEO help web sites and often on special pages created by search engine companies to specifically address search engine optimization questions. Legitimate search engine optimizers, whether individuals or companies, will exclusively and appropriately use white hat tactics. Make sure they do before hiring them, or you risk losing your money.
For more information on acceptable SEO practices, check out http://static.googleusercontent.com/external_content/untrusted_dlcp/www.google.com/en/us/webmasters/docs/search-engine-optimization-starter-guide.pdf