Information Technology Reference
In-Depth Information
How do Web
applications
work?
Imagine that your friend Aimee is sitting at her computer, navi
gating through the Web and exploring a variety of sites. She goes to a
search engine to locate possibilities for tonight's entertainment in
Boston, and as she does so, an icon on her desktop indicates she has
just received new email. She clicks to her email account, determines
the new mail is spam, deletes it, and clicks back to her browser to
continue her search for evening activities. The search engine provides
her with several sites that seem related to what she's looking for, from
newspaper Web sites, to entertainment guides, to travel brochures. As
she scans these sites and learns what she wants to know, a few pop
up ads appear offering her subscriptions to entertainment magazines
and discounts on tours of Boston. After a few minutes, Aimee has fin
ished scoping out Boston's evening scene, so she logs off the network
and calls her friends to plan for the night's activities.
This brief Internet work involved a number of Web applications
(search engines, email, spam, popup ads), but how did they work?
How did the search engine know which sites to direct Aimee to so
quickly? Why did she receive a piece of unsolicited email? How
were the popup ads chosen to cater to her query? To discover the
answers to these questions, we need to understand some basics of
these computer applications.
All computer applications depend upon computer programs to
provide specific instructions that describe exactly what the com
puter is to do. The instructions, or sequence of steps for perform
ing work, are called an algorithm , and Web applications (or other
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