How to work SEO step by step? SEO Tuts
IR services for finding Web content include the following:
Crawler search engines
rely on classy computer programs called spiders or bots that crawl the Internet to locate web content, links and other content which are stored in the engine’s page source. Google and Bing are based on crawler technology.
are considered listings of web-page created and maintained by humans. Because websites are only included after being studied by a person, it is less likely that search results will contain irrelevant website. Instances of general directories contain Open Directory Project (dmoz. org), Best of the Web (botw.org), and Looksmart.com.
Hybrid search engines
syndicate the results of a directory created by humans and results from a crawler search engine, with the goal of providing both accuracy and broad coverage of the Internet. Yahoo.com, the third most popular marketable search tool, uses a hybrid approach to information search.
accumulate the results from other search engines. For example, Dogpile.com generates listings by combining results from Google and Yandex, two crawler-based engines, and Yahoo, a hybrid search tool.
Semantic search engines
are considered to find information based on the environment and meaning of Web content, not simple keyword matches. Their goal is to intensely increase the accuracy and usefulness of search results