Google Inc.'s move to offer its own Web browser begs a question about a technology that most people now take for granted: What exactly is a Web browser?
The short answer is that it is a piece of software that takes us where we want to go, whether to buy a pair of pants or call up a bus schedule. To understand what a browser really does, though, it helps to understand why it was invented.
Computers were once isolated calculation engines. A user walked up to them, inserted a stack of punch cards or pushed some buttons, and waited for an answer. Later users could interact with a specific system using terminals sold by each computer maker, a phase followed by networks that could connect different kinds of computers run by individual organizations.
In the 1970s, researchers agreed on a set of specifications to send packets between those dissimilar systems -- akin to the address scheme the post office uses to route letters. Thus was born the Internet.
But viewing information on someone else's computer still wasn't easy. For one thing, the information might be stored in a database or other proprietary software that varied among organizations. Tim Berners-Lee, the man credited with inventing the Web, wanted to break down those barriers.
He built on a technology known as hypertext -- the notion of establishing links to connect any concept, or document, to any other. That required developing and popularizing three sets of rules for creating and exchanging documents.
One is hypertext transfer protocol, or HTTP, which establishes specifications for linking documents. Another is an address scheme for finding documents, known as a universal resource locator, or URL. Third is a way to create documents in a consistent format, known as hypertext markup language, or HTML.
But there was still one key element missing: a piece of desktop software to display documents created using HTML, and respond to the communications instructions based on HTTP and URL. So Mr. Berners-Lee created the first browser, a type of program that would later be refined by Netscape Communications Corp., Microsoft Corp. and others.
Today's browsers have been updated to do additional tricks. By using small programs, known as plug-ins, they can allow users to view videos and animations.
But browsers still must manage the more basic chores of displaying documents and navigating between them. When a user clicks on a link on a Web page -- or types a URL into the address line and hits return -- the browser sends a request for information that is converted into data packets and sent out to the Internet.
The request is routed through organizations that manage directories of domain names, and store numerical addresses associated with those names. Once that request reaches the server with that address, it responds by sending a new Web page that bounces back around the Internet to pop up on the user's browser.
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