What exactly is a search engine?

[Jackie]

For anyone to start a career in SEO, one must know the meaning, the real sense of the words SEARCH ENGINES. What are these?

Search indexes or search engines are the predominant type of search tools you’ll run across. Originally, the term search engine referred to some kind of search index, a huge database containing information from individual Web sites. Google’s vast index (www.google.com) contains over 3 billion pages, for instance. Large search-index companies own thousands of computers that use software known as spiders or robots (or just plain bots — Google’s software is known as Googlebot) to grab Web pages and read the information stored in them. These systems don’t always grab all the information on each page or all the pages in a Web site, but they grab a significant amount of information and use complex algorithms to index that information. Google is the world’s most popular search engine.

[Manny]

I wonder how Google utilizes their index. That's huge, but they return results with a blink of an eye. Excellent algorithms they have! Isn't it that there are also other search engines around? Do they have also other algorithms? Say, AOL, Yahoo, etc.?

[Charles]

Jackie, with due respect, let me answer Manny's question. Basically, most search engines have the same algorithms, but different databases. However, take note that AOL doesn't have its own search system. Search system? Well, this is the system being used by the search engine to display results. Unfortunately, AOL overrides with Google to return their results. Quoting from Jackie, Google is the world's giant in search engines.