According to Wikipedia:
Search engine optimization or (SEO) as it is called is the process of improving the visibility of a website or a web page in search engines via the “natural” or un-paid (“organic” or “algorithmic”) search results.
Local business and search engine optimization just works.

SEO can target many different kinds of search, such as local search, search for a specific industry and many different niches within that industry. You can search for a product, a photograph or even a video. Just because you have a website online it does not mean you can be found online. Giving the search engines what they are looking for does.