Why is it that some of the (newer?) URLs have foregone the initial “www”? For purposes of simplicity? Wouldn’t it be more expedient to drop the initial three letters as a rule and add a suitable prefix in special circumstances?
I asked this one before & that www is not necessary. You can get to a web site without using that. It’s just chaff.
Unless some idiot webmaster got the idea to use as a mailserver: site.com in that case they have to use http://www.site.com
Be careful here. This will not always work, though it often does since the Web is the most popular use of the Internet. If the host address of a domain (something.com) happens to be the same as that domain’s WWW server, (www.something.com) then this will work. If they’re different, then it won’t.
Most commercials drop the “www” these days for the sake of simplicity. They set their servers up so the domain name alone will work.
It’s easier to think about yahoo.com then doubleyoo-double-yoo-double-yoo-dot-yahoo-dot-com. 
A URL specifies a protocol followed by a domain followed by a path.
The protocol is the http:// or ftp:// or https:// or gopher:// or news:// or …, and specifies in what form the information is to be transferred.
The domain is the http://www.samplesite.com part. It is a hierearchical structure lke a file path but it is read right to left. “www.amazon.com” means “in the commercial Top Level Domain, the sub-domain amazon, the computer named www”. Actually, in this sense a “computer” could physically be several computers, and one computer could be hosting several domains. So it’s a “logical computer”, not a physical computer.
The path is the /… part. If it’s just a slash, then a default document (usually index.htm or index.html for http protocol) is meant. If there is no path, then usually the same thing happens but sometimes an error happens (depending on ow the server is set up). If it is more than a slash, then it is read left-to-right and is just like a DOS or WIndows file path.
The same thing can be done with the domain part; amazon.com means the same as http://www.amazon.com because they’ve set it up so that amazon.com defaults to http://www.amazon.com. But not all domains are set up that way. And there can only be one default; straightdope.com gets you to http://www.straightdope.com but not to boards.straightdope.com.
[note: I edited out the accidental porn link. -manhattan]
[Edited by manhattan on 08-21-2000 at 08:37 AM]
damn VB … try again
The protocol is the http:// or ftp:// or https:// or gopher:// or news:// or …, and specifies in what form the information is to be transferred.
The domain is the www.xxx.com part. It is a hierearchical structure lke a file path but it is read right to left. “www.amazon.com” means “in the commercial Top Level Domain, the sub-domain amazon, the computer named www”. Actually, in this sense a “computer” could physically be several computers, and one computer could be hosting several domains. So it’s a “logical computer”, not a physical computer.
The path is the /… part. If it’s just a slash, then a default document (usually index.htm or index.html for http protocol) is meant. If there is no path, then usually the same thing happens but sometimes an error happens (depending on ow the server is set up). If it is more than a slash, then it is read left-to-right and is just like a DOS or WIndows file path.
The same thing can be done with the domain part; amazon.com means the same as www.amazon.com because they’ve set it up so that amazon.com defaults to www.amazon.com. But not all domains are set up that way. And there can only be one default; straightdope.com gets you to www.straightdope.com but not to boards.straightdope.com.
Thanks Jon and others. Enlightening.
Understood, but let me ask something more.
A sub-domain is (I believe): http://www.domain/sub-domain.com
While this is a three level domain: http://www.domain/sub-domain/sub-sub-domain.com
The one I don’t understand is: http://www.something-here.domain/sub-domain/sub-sub-domain.com
Is the ‘something-here’ capability an example of what you can do when you have a dedicated server (but isn’t feasible on shared or virtual servers) ?
And also, is WWW restricted to 3 level domains does anyone know (no reason, just curious on the last question) ?
Not quite, London. There’s almost never a .com after the slashes. The domains and sub-domains go right to left, and are separated by periods, so we have http://subdomain.domain.topdomain . (topdomain is .com , .edu , .uk , or one of the other top-level domains.) Then, if you have a slash after the top-level domain, you’re into directories on that computer, so you can have http://subdomain.domain.topdomain/directory/subdirectory/file.html . This means “The file caled ‘file.html’, in the directory called ‘subdirectory’, in the directory called ‘directory’, on the computer called subdomain, accessed via the computer called ‘domain’, accessed via the top-level domain computer caller ‘topdomain’.” So far as I know, there’s no limit on the number of possible subdomains, but they’re usually kept short so folks can remember them, and the only limits on the number of subdirectories are those imposed by the OS of the computer that’s hosting them.
Nice, Chronos. Thanks. Think I was getting my .com’s confused with html/htm’s.
So, anything to the right of the top level domain (e.g. .the com type suffix) is a directory within the domain/site and anything to the left is a sub-domain.
Thinking about how to build sub-domains into a site hierarchy prior to ftp-ing…….
Hmmmm, presumably it’s just a file naming exercise. You would have the index.html coming off the root so you rename that from http://www.domain.com/index.html to
http://www.sub-domain.domain.com/index.html.
But that leaves the rest……oh, you type the sub-domain into the root folder before the top level domain ?
Any good ?
The authoritative reference for what is a URL is RFC2396.
There are other, less commonly used, forms. For example, to connect to (for example) application port 801 using HTTP protocol: http://www.media3.net:801
It’s not just a file-naming exercise. You have to get your site host to tell the DNS servers that www.subdomain.domain.com is equivalent to an IP address that your site host has linked to the system that holds your site. That part of the URL is handled by the DNS system.
To amplify a bit:
Your directory structure goes after the Top Level Domain, separated by a slash. This can be illustrated by the fact that http://www.ratynski.com/index.htm is the same thing as http://www.fleming-group.com/Ratynski/index.htm. Or, to download some of the components of the Windows 2000 Resource Kit (which is kept in directory reskit\Win2000 on Microsoft’s FTP server), ftp://ftp.microsoft.com/reskit/win2000/.
Thanks, Jon. Yes, I thought the host would have to do a little more (presumably there might be more cost involved for me, at least on set up) but I was curious about the ftp part from my end.
Thanks also for the Ref. I noticed that Tim Berners-Lee was still in the forefront of net protocol standardisation in 1998 – don’t know why but I assumed things had moved on.
Cheers.
He’s the Director of the WWW Consortium.
I use Red Shift a lot. When I asked them about redshift.com they said it was setup as a mail server when they first opened & lots of people still use it for their mail, thus, people have to use http://www.redshift.com to get to the web address.
Never had that experience. Either it sends me to the regular site or says “Page doesn’t exist”.
(Hey techies: I’m getting more than I bargained for.:D)