Search Engine Optimization (SEO)
Search engine optimization (SEO) is the process of improving the volume and
quality of traffic to a web site from search engines via "natural" ("organic" or
"algorithmic") search results for targeted keywords. Usually, the earlier a site
is presented in the search results, or the higher it "ranks", the more searchers
will visit that site. SEO can also target different kinds of search, including
image search, local search, and industry-specific vertical search engines.
As a marketing strategy for increasing a site's relevance, SEO considers how
search algorithms work and what people search for. SEO efforts may involve a
site's coding, presentation, and structure, as well as fixing problems that
could prevent search engine indexing programs from fully spidering a site.
Other, more noticeable efforts may include adding unique content to a site,
ensuring that content is easily indexed by search engine robots, and making the
site more appealing to users. Another class of techniques, known as black hat
SEO or spamdexing, use methods such as link farms and keyword stuffing that tend
to harm search engine user experience. Search engines look for sites that employ
these techniques and may remove them from their indexes.
From: http://www.wikipedia.org