Internet search engines

The terms Google bomb and Googlewashing refer to the practice of causing a web site to rank highly in web search engine results for unrelated or off-topic search terms by linking heavily.

An index term, subject term, subject heading, or descriptor, in information retrieval, is a term that captures the essence of the topic of a document.

The robots exclusion standard, also known as the robots exclusion protocol or simply robots.

Collaborative filtering (CF) is a technique used by recommender systems.

In Internet marketing, search advertising is a method of placing online advertisements on web pages that show results from search engine queries.

Query languages are computer languages used to make queries in databases and information systems.

Wide Area Information Server (WAIS) is a client–server text searching system that uses the ANSI Standard Z39.

The deep web, invisible web, or hidden web are parts of the World Wide Web whose contents are not indexed by standard search engines for any reason.

This is a list of search engines, including web search engines, selection-based search engines, metasearch engines, desktop search tools, and web portals and vertical market websites that have a search facility for online databases.

Info.com is a metasearch engine which provides results from leading search engines and pay-per-click directories, including Google, Yahoo!, Bing.

Grub is an open source distributed search crawler platform.

Search engines are listed in tables below for comparison purposes.