The database(s) against which queries are resolved. All of the major search engines maintain multiple indexes. Each is a separate, distinct database, either physically (kept in separate files) or virtually (logically segmented portions of a master database). The expression database is probably inappropriate for describing what the search engines maintain. When you see me refer to Main Index, think of that as the “static Web page index”. Other indexes may include Image Indexes, News Indexes, and Blog Indexes. I have some ideas on how these various indexes are built, but I don’t expect to share them on this blog.

The process of adding information about Web content to a search engine’s database about the Web. The indexing process may entail considerable effort depending upon the complexity and applicability of the document. A shortened form of the term search engine indexing.

The study or discipline of searching for documents in databases. IR Science provides much of the foundation technology for Web search.

The highly risky search engine optimization technique of making text on a page invisible either through color changes within HTML, the placement of graphics, or adjustments to one's cascading style sheet. This is one of the more common causes of the Google Death Penalty.

The term that describes the amount of information on the web that is not indexed by search engines. Another term to describe this is "Deep Web". The Deep Web is not a part of the surface web, and it is speculated that the invisible web is substantially larger than the surface web.

A specific Internet Protocol number for computers on the Internet. IP addresses are generally unique for an individual computer, computers behind a firewall may share an IP address for the purposes of machines outside the internet.

The process of determining an IP Address.

The act of hiding a computer's actual IP address and reporting another address to other computers being accessed. This is generally done to hide the source of nefarious activities.