What's A Search Engine And How Does It Work?

Search engine is the popular term for an information retrieval (IR) system. While researchers and developers take a broader view of IR systems, consumers think of them more in terms of what they want the systems to do — namely search the Web, or an intranet, or a database. Actually consumers would really prefer a finding engine, rather than a search engine.
Search engines match queries against an index that they create. The index consists of the words in each document, plus pointers to their locations within the documents. This is called an inverted file. A search engine or IR system comprises four essential modules:
A document processor
A query processor
A search and matching function
A ranking capability
While users focus on "search," the search and matching function is only one of the four modules. Each of these four modules may cause the expected or unexpected results that consumers get when they use a search engine.

Search engine allow a user to type a query and shows the result according to that query. Search engine stored information in their database and when a user type something in the search area and press enter then search engine try to match that word or sentence with the data stored in the database and show those pages which match with the query in result. Search engines use very powerful algorithms for searching data. Because searching specific data in huge database is not easy task. Search engines use millions of hard disk to store all the data. Now you can imagine that how difficult is the process of searching and how powerful algorithms are used who search all these hard drive in few seconds and provide the exact match with query.
If you see on internet then you will find many search engines but some of them are really good and provide accurate data. Some top search engines are Google, yahoo and Msn. All these search engines used powerful algorithms and latest technology to provide data in few seconds but accuracy is different on each search engine. If you type same query on different search engines then you will see different results.