Search Engine: A program that aims to search for answers to questions that are presented in the form of a set of information, where the search engine shows a list of pages, these pages include terms found in the query phrase entered, as users can By searching specifically for photos, videos, news articles, or website names,  The search engine Archie (English: Archie) is the first search engine created, which was used to search for File Transfer Protocol (FTP), and Veronica’s engine (English: Veronica) was the first engine Text-based search, today the Google search engine is the most popular and prevalent, and examples of other popular search engines are AOL, Ask.com, Baidu, Bing, Yahoo.
Search Engine Components
Search engines, online, consist of a consistent set of programs, which include: 
1: spider or as a web crawler who can access each page, or an analog page in each Web site, which can be searched for, then read it, and uses crawler hyperlinks on each page To be able to find and read other pages on the site.
2:A program that receives the user’s search request, compares it to the entries in the list, and then displays similar results.
A program that creates a huge list of read pages3:
Important Search engine Information
The main search engines are Google search engine (Google), Yahoo (Yahoo), Alta VST (AltaVista), and non-Lycos, which schedule a large part of the network information, and provide search results that can be displayed.
–Some search engines specialize in content, and these engines customize the part of the web that is searched, thus displaying only the part of the data that is required for a particular type of product.
–Some sites allow the user to enter a search request in an easy language such as: “How is the weather in London today?” and from these sites: the Ask Site.
–Some major search engine companies license or sell their search engines to be used on individual sites.
↑ “Search engine”, www.britannica.com, Retrieved 10-4-2018. Edited.
↑ “Search engine”, Www.computerhope.com, 22-9-2017, retrieved 10-4-2018. Edited.
↑a b c t w “Search engine”, www.searchmicroservices.techtarget.com, Retrieved 10-4-2018.