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. Usually, the earlier a site is presented in the search results, or the higher it ""ranks," the more searchers will visit that site. The leading search engines, Google, Yahoo! and Microsoft, use crawlers to find pages for their algorithmic search results.
Search Engine Marketing (SEM)
Search Engine Marketing is a method of Internet marketing whose purpose is to increase visibility during search engine queries. You can do this by selectively choosing the HTML and website content in order to appear higher in a particular search result. Search Engine Marketing are short texts that appear along the side of a search result. They are referred to as "sponsored links" or "sponsored results"