How Does a Search Engine Work?

Did you ever ask, "How does a search engine work?" or do you simply take their function for granted? If you sometimes find yourself disappointed with search engine results, understanding how they decide what pages to show can help you search more efficiently.

It's All About Ranking
When you type a phrase into a search engine, the results you get are based on what the search engine thinks you want to find. Since the software can't read your mind, it gives you thepages that most people click on when they type in that phrase. For example, typing "Barack Obama" in Google will get you news results first, since most people click on news links after  they type his name. You'll also find the president's Web page, his MySpace page, a Wikipedia page about him and a link to the White House home page. If you don't find what you need, you can click on the next page of results, and so on, until you find the right information.

For most searches, this helps you find what you need. But try looking for information about a video game or popular TV show and you'll be clobbered with spam. Searches for songs return page after page of lyrics and YouTube video links, when what you wanted was some album information. Fortunately, there are some simple ways to make a search engine work for you, rather than against you.

Advanced Searching
All of the major search engines share lesser-known features that can make searching much faster and more successful. By using a few symbols from your keyboard, you can radically alter the results you get.

• Quotation marks: Put your entire search phrase in quotes. This tells the search engine to look for pages that have that exact phrase, with the words in that exact order. This is very helpful if you're looking up names or titles that use a lot of common words.
• + symbol: Adding a plus sign to your terms tells the search engine to give you pages that contain those exact words. Say you're searching for information about The Beatles' song Yesterday. Simply typing "yesterday" won't give you Beatle-specific results, although you will get some. If you change the search to yesterday +beatles, you get pages that deal with The Beatles music. If you know the results you want are on a certain Web site, you can include its domain name to narrow your results; for example, yesterday +beatles +amazon.com will give you search results from Amazon at the top of the list, followed by sites that link to Amazon.
• - symbol: A minus sign tells a search engine to exclude results that you don't want. If you use the yesterday +beatles search, you'll get a lot of links to videos and lyrics. If you don't want those, change the search to yesterday +beatles -lyrics -video, and you'll find more specific information about the band and the song. You'll sometimes need to minus out a lot of terms to find what you want, such as the Yesterday Beatles Tribute Band in this example, but it's much quicker than wading through pages of search results. You can also exclude domain names, -amazon.com, for example, to filter out certain types of sites.