See subject.
Well, you’re posting to one right now, boards.straightdope.com.
www. is a prefix in the url that was meant to show that it was a web address ( world wide web ) as opposed to ftp. or mail. or whatever depending on the server. It is now regarded as unnecessary by the type of person who moos “Simplify, simplify.” — to themselves and anyone who bothers to listen to them.
So you can set your website to accept only http:// or http://www, or to accept both. In the first case you issue a redirect to send all of the unwanted type to the preferred type. Usually in the .htaccess file at the root of the server.
It’s purely a faddish choice either way. But, bearing in mind browsers increasing tendency to conceal parts of the url, I imagine that not having www. will be followed by not having http:// eventually; and finally urls will be opaque to the user.
www., apart from looking better, serves in print to show that a line indicates an url, and not random words.
The www part is a convention, not a standard. In other words, it’s there because people expect it to be there, not because it has to be there. That expectation is now dwindling, and so is the occurrence of it.
In theory www.[name].[domain] and [name].[domain] don’t have to lead to the same page any more than boards.straightdope.com and www.straightdope.com do, but in practice they almost always do.
There are certain rules that apply to URLs. On top of this, there are a lot of informal standards that people tend to follow that aren’t actual standards, but most people just do it that way out of convenience or tradition.
Back in the old days of the internet, before WWW became the “internet” to most folks, one of these unwritten conventions was that the first part of the URL would be the machine name, and this name would often indicate its purpose. This would be followed by the company or organization name, and the bit at the end would be .com or .org or .edu depending on if it was a business or an organization or an educational facility, for example.
So you would have things like ftp.companyname.com would be the company’s ftp server, for example. When WWW started becoming popular, it only made sense to start naming the web serving machines www.companyname.com. You can even see that on the dope here. The URL www.straightdope.com points to the straight dope web page, and board.straightdope.com points to the message boards. Back when this site got started, chances are there were separate machines dedicated to each of those purposes.
There was no written standard for it, but as the WWW became popular, it also became common for companies to redirect companyname.com (with no www or anything else in front of it) to the same machine as www.companyname.com. If you try straightdope.com for example, it takes you to the same page as www.straightdope.com. This has to be done by the folks setting up the domain names. If a company/organization doesn’t intentionally set it up, it doesn’t work. So this is why it only works for some sites and not others. There’s no standard for it. It’s just a convention.
It used to be that (machine name).(company name).(top level domain) would usually resolve to a single machine. These days, it’s not so straightforward. Companies and organizations will still often follow those conventions, but the message board software and the web server may be the same machine, or they may be different machines, or they may be part of virtual machines on a larger server, or they may just be part of a server that also contains many other domains in different parts of its disks.
Even the old typical www.companyname.com is being abandoned by a lot of folks. You’ve got things like youtu.be which, although perfectly acceptable by the standards 15 or 20 years ago, would have definitely been frowned upon then. The ease of google searches to find things now really helps. Back in the older days, people used www.companyname.com because it was the only easy way to let your customers find your web site. These days that sort of thing doesn’t matter so much.
Even if you aren’t using it promotionally, it’s generally a good idea to still have the old style name, though, even if it just redirects to the “official” URL. URL shorteners, like youtu.be, are an exception because they always redirect to something else anyway.
MIT is an interesting example, here. They were, of course, one of the early adopters both of the Internet and of the World Wide Web. As such, they ended up setting up their web site before “www.” became the convention, and so ended up calling their web server “web.mit.edu”. Nowadays, www.mit.edu will also work, but they’ve still kept the old address around, too.
Yeah, this is one of the few sites that doesn’t automatically restore the www at the front. In fact. there are two DNS entries (at least, I can’t search to be sure of there being no other !)
http://boards.straightdope.com
and
www.boards.straightdope.com
The use of the www one just results in the www being REMOVED from the webbrowsers URL… because the website sends a redirect , which is always to boards.straightdope.com
The system administrators of the computers do never feel they must use the hostname that has the protocol at the front. (the system admin may point a web browser at mail.domain.com, or use pop3 from www.domain.com … )
A server hardware (or virtual instance, eg a vmware instance), can have many services, that can communicate with many protocols…
Its useful to provide one DNS name for each server in common use, (eg the web server that the public uses)… so that one can move the service from one server to another easier. Just move the service and update the DNS entry with the new ip address (or move the ip address from one hardware to the other, which sometimes is easy and is sometimes rather hard. Not really impossible but for paperwork and money… )
If the large organisation put everything on one ip address (or one specific set of),
the one device (or every device of the set) has to answer all the protocols… which is unworkable if they grow large… if they run email on their own servers, but pay someone to host their website… well its inconventient too , as upgrades would have to ber everything all at once, rather than ‘divide and conquer’ …
It may be that these days the domain can get the ip address of the webserver, since its only web addresses that are frequently typed, other servers are configured once in a while ,eg by putting the address into the email program.