How Internet Search Engines Work

   

"Spiders" take a Web page's content and create key search words that enable online users to find pages they're looking for.

Web Crawling

When most people talk about Internet search engines, they really mean World Wide Web search engines. Before the Web became the most visible part of the Internet, there were already search engines in place to help people find information on the Net. Programs with names like "gopher" and "Archie" kept indexes of files stored on servers connected to the Internet, and dramatically reduced the amount of time required to find programs and documents. In the late 1980s, getting serious value from the Internet meant knowing how to use gopher, Archie, Veronica and the rest.

Today, most Internet users limit their searches to the Web, so we'll limit this article to search engines that focus on the contents of Web pages.

Before a search engine can tell you where a file or document is, it must be found. To find information on the hundreds of millions of Web pages that exist, a search engine employs special software robots, called spiders, to build lists of the words found on Web sites. When a spider is building its lists, the process is called Web crawling. (There are some disadvantages to calling part of the Internet the World Wide Web -- a large set of arachnid-centric names for tools is one of them.) In order to build and maintain a useful list of words, a search engine's spiders have to look at a lot of pages.

How does any spider start its travels over the Web? The usual starting points are lists of heavily usedservers and very popular pages. The spider will begin with a popular site, indexing the words on its pages and following every link found within the site. In this way, the spidering system quickly begins to travel, spreading out across the most widely used portions of the Web.

Google began as an academic search engine. In the paper that describes how the system was built, Sergey Brin and Lawrence Page give an example of how quickly their spiders can work. They built their initial system to use multiple spiders, usually three at one time. Each spider could keep about 300 connections to Web pages open at a time. At its peak performance, using four spiders, their system could crawl over 100 pages per second, generating around 600 kilobytes of data each second.

Keeping everything running quickly meant building a system to feed necessary information to the spiders. The early Google system had a server dedicated to providing URLs to the spiders. Rather than depending on an Internet service provider for the domain name server (DNS) that translates a server's name into an address, Google had its own DNS, in order to keep delays to a minimum.

When the Google spider looked at an HTML page, it took note of two things:

• The words within the page
• Where the words were found

Words occurring in the title, subtitles, meta tags and other positions of relative importance were noted for special consideration during a subsequent user search. The Google spider was built to index every significant word on a page, leaving out the articles "a," "an" and "the." Other spiders take different approaches.

These different approaches usually attempt to make the spider operate faster, allow users to search more efficiently, or both. For example, some spiders will keep track of the words in the title, sub-headings and links, along with the 100 most frequently used words on the page and each word in the first 20 lines of text. Lycos is said to use this approach to spidering the Web.

Other systems, such as Alta-vista, go in the other direction, indexing every single word on a page, including "a," "an," "the" and other "insignificant" words. The push to completeness in this approach is matched by other systems in the attention given to the unseen portion of the Web page, the meta tags.  Learn more about meta tags on the next page.

15 Simple Things That Still Make You Happy

15 Simple Things That Still Make You Happy.

No matter how Old or Rich or Awesome or Famous you become, these 15 of the simplest things from everyday are bound to bring a smile to your face.

Life is full of surprises and surprisingly simple pleasures that money cannot buy. Well, technically money can buy most of them but that’s really not the point here. Real happiness is getting something when you least expected it. In all honesty, we all age.. But seldom do we grow up. And when it comes to the instances below we think it’s safe to assume that we all find a little bit of joy in most of the situations.

1). Mother Serving Your Favorite Food

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No matter how expensive the restaurant, no matter how critically acclaimed its chef, no matter how delicious the food… It will never ever in a friggin gazillion years come close to our mother’s ghee laden ‘Aloo ka parathas’ … Period!!

2). Driving Alone On An Open Stretch Of Road

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We've all done that... You see an open stretch of empty road, put on your favorite song and sing your heart out. Where else can you get this joy?

3). Finding Money In Your Jeans Pocket

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Too much month at the end of your money? Wondering how to survive that one day until payday? ... Imagine finding a 500rupee in your jeans pocket!! What worldly pleasure can match that feeling?

4). Someone says, "I'll pay for you."

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What is better than beer? ... Free Beer!!! We all love it, don’t we? That one statement which puts a evil sly grin of content on our faces! What is the fun in buying your own beer!!

5). Realizing Someone Is Flirting With You.

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This one applies only to guys. Plainly because guys are normally the one’s chasing the women and not the other way around. It is not a everyday thing which is what makes it so special.

6). Jukebox Plays A Song You Know

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Friends have dragged you into a place which usually plays drab music. Something you don’t listen to and cannot associate with. But then suddenly the jukebox plays a tune you know or maybe a part in that long lyrical charade and this is exactly how you react.

7). Leaving From Work Early

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Life is about finding those small packets of happiness even if it is something as simple as leaving from work an hour earlier!!

8). Someone You Like Gives You A Hug

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There is no better feeling in this world than getting a warm hug from the one you like.

9). Be In An Elevator With Hot Women/Men

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Now that is a fantasy every man/woman is bound to have. We wish for these moments of glee in our otherwise uneventful life. Caught in a lift with hot women/men around, Bumping into an old fling, Sitting next to a beautiful/hot woman/man on the bus ride to work!!

10). Unwraping A Gift

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It doesn't matter how old we are. Getting a gift and the suspense of unwrapping it turns us into adolescent young boys and girls. And that will never change!!

11). Bubble Wrap!

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Need I say more?? It just doesn't and never will be a childish thing to do. You see bubble wrap and the first reflex is to grab the biggest sheet of it.

12). When You Have A Friend You Can Get Weird With

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We love that 'One' friend we can get weird with. He not only understands us but shares our craziness!!

13). Meeting A Long Lost Friend

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You know that person; you grow up together, literally shared everything in life together but eventually lost touch growing up. And one fine day, you meet him in the most unexpected way. Happiness?

14). Gossiping About Someone You Hate.

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It doesn’t matter if you’re a man or a woman… Both love to gossip and bitch about the one they hate. A sly form of happiness but happiness nonetheless!

15). Petrichor.