What is a search engine ?

• What do you do when you need to find something on the Internet? In most cases, you pop over to one of the major search engines and type in the term or phrase that you’re looking for and then click through the results, right?

WHAT IS A SEARCH ENGINE ?

• You know the basic concept of a search engine. Type a word or phrase into a search box and click a button. Wait a few seconds, and references to thousands (or hundreds of thousands) of pages will appear. 
• Then all you have to do is click through those pages to find what you want a search engine is a piece of software that uses applications to collect information about web pages. 
• The information collected is usually key words or phrases that are possible indicators of what is contained on the web page as a whole, the URL of the page, the code that makes up the page, and links into and out of the page. That information is then indexed and stored in a database.
• The process of collecting information about web pages is performed by an agent called a crawler, spider, or robot. The crawler literally looks at every URL on the Web, and collects key words and phrases on each page, which are then included in the database that powers a search engine.