A search engine is a software system that is designed to search for information on the World Wide Web. The search results are generally presented in a line of results referred to as search engine results pages (SERPs). The information may be a mix of web pages, images, and other types of files. Some search engines also mine data available in databases or open directories. Unlike web directories, which are maintained by human editors, search engines also maintain real-time information by utilizing an algorithm on a web crawler.
The most popular search engines are: