SEO Glossary: I

impressions : The number of times an ad appears in search results to search engine users.

incestuous links : Links to the properties of an individual or organization, or among a group of friends' sites, where the links are then passed off as legitimate links from outside sources.

index : The database of Web sites that a search engine pulls results from in response to search queries.

indexing : The process of taking raw data and categorizing it, removing duplicate information, and generally organizing it all into an accessible structure (think filing cabinet versus paper pile).

internal links : Links on a Web site going to other pages within that site.

internal site search engine : A search engine that searches only a particular Web site.

Internet backbone : The main hub connections of the Internet, which are primarily located in major cities around the world (Los Angeles, Denver, New York, and so on).

Internet forum : A message board where users can log on and post about topics on a related subject.

Internet Protocol (IP) address : The numeric code that identifies the logical address where a computer, server, or site resides on the Web.

ISP : An acronym for Internet Service Provider.