Engine
A search engine is essentially query processing. It is a form of information retrieval that helps one to answer questions
The search results are generally presented in a line of results, often referred to as search engine results pages (SERPs).
Some search engines also mine data available in databases or open directories. Unlike web directories, which are maintained only by human editors, search engines also maintain real-time information by running an algorithm on a web crawler.
query
See also PageRank