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This is not a programming question, but something I was curious for a long time. I am a web developer myself, but do not know the answer to this question. I notice some websites have just http:// in their address, with no www. (eg. http-colon-//delicious) and other websites have www. in their address (eg. http-colon-//www-dot-yahoo-dot-com)

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migrated from May 17 '10 at 8:03

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closed as off topic by Gnoupi, Jeff Atwood May 17 '10 at 8:15

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Where's the question? – Matti Virkkunen May 17 '10 at 8:06
You can have opinion from people who made these sites at this link: – Gnoupi May 17 '10 at 8:16
The basic idea is that "www." is part of a computer's name. (Whether that is actually true may be blurred by the fact that some websites have multiple computers acting as web servers. Let's ignore the complications from that design.) A single IP address (in simple terms, you can often think of that as a single computer) can have multiple names, such as both and Whether is a valid name, or whether it even exists, depends on the decision made by whoever controls (and bothered to set up) the ( domain name. – TOOGAM Mar 9 at 19:02

The www is not required, so some sites dispense with it.

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I hate having to type www. And nothing gets more annoying than sites that do not properly DNS themselves, and force you to type www. – Mitch Dempsey May 17 '10 at 8:05
you should be aware that there are some kind of annoying cookie side effects when your base domain does not begin with www but that is more of a programmer issue than a user one. – Jeff Atwood May 17 '10 at 8:14

The www is a convention from when the web was small and much less important than it is today. It is entirely optional (although can be useful for a domain to organize its cookies)

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www is the conventional prefix, but it is not mandatory. Particularly if you already have a subdomain, skipping the extra www prefix just leaves a shorter address: rather than reads better.

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The www part of the URL is a sub domain. It is completely at the discretion of the owner of the domain whether or not www or any other sub domain is used.

There are many sites out there that prefer not to use www and even some that think it should be deprecated. Check out, who have "validated" thousands of sites that don't use the www part of the domain.

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