Date: June 10, 2001
From: EscVector
Here's the slightly edited original post with a few more links.
Also, thanks NoClue for typing the original and keeping the post alive 
What we are talking about here are FQDN or
Fully Qualified Domain Names. These names are hierarchical,
or rather, they are like clicking on the C drive folder in Explorer, then click on a
subfolder, and then click on a subfolder within a subfolder, or you could say they are
like finding a street address, state, city, street etc. The dots separate each address
level. Domain Names consist of at least two parts, TLD or
Top Level Domain such as .com, .edu, .uk, etc, and a subdomain, such as compududes, or
microsoft.
The hierarchy is managed through the DNS or
Domain Name System network.
Since the internet is big, maintenance of the DNS directories is delegated to various
organizations starting with ROOT or "." Here's
a list of the root servers located around the world. Network Solutions, aka
NSI, through an agreement with ICANN, now manages this root which contains the directions to all the
TLDs.
NSI also controls the registration of all COM NET ORG and EDU TLDs. In an effort to
bring the open market to the name registration business and avoid dealing with the U.S.
Justice Department, NSI agreed to allow third-party registrations of the TLDs COM,
NET, and ORG through what are known as Registrars.
You need to be an accredited degree factory to get an EDU TLD. Registrars are the ones you
pay to obtain a name like CompuDudes.com, CompuDudes.net, or CompuDudes.org.
TLDs like .TV or .MD are sold through agreements with
their respective countries. Each country can set their own rules and price.
This is where it gets a little tricky. You need to have at least two working DNS
servers in order to register a Domain Name. Usually, small business and individuals don't
have a DNS server, so they pay their Internet Service Provider to keep the Domain name on
their DNS servers. As competition between Registrars heats up, this process is becoming
more transparent to the consumer, but the technical qualifications remain the same.
Larger corporations usually have control over their own DNS serves and are what is know
as the Start-of-Authority for their registered names. As an example, take MICROSOFT.COM.
Microsoft corp. controls anything that would be put in front of "MICROSOFT",
such as TECHNET.MICROSOFT.COM. The TECHNET portion of this FQDN is know as a SubDomain
much like a subdirectory on a harddisk. The subdomain can be a server or a directory or
can be on the same webserver as the main site.
The trick is, it can be anywhere that the company's DNS admin wants it to be although
it's usually a server. Also, it can be any name that DNS admin wants, WWW, TECHNET,
SERVER1.
Your question asks what's the difference between:
1. http://www.domain.com/
2. http://www.something.domain.com/
3. www.domain.com/something.html
1. http://www.domain.com/ and http://www.something.domain.com/ are FQDNs.
Broken up, the WWW, which stands for World Wide Web, is usually the designation for a web
server. It could just as easily say "WEBSERVER.DOMAIN.COM" There is no
technical qualification to the WWW name.
Specifically, http://www.domain.com/ has one subdomain past the registered name and
http://www.something.domain.com/ is two subdomains past the registered domain.
Within an organization, someone is usually given control over each subdomain to make
administration easier. The organization that added these subdomain is responsible for
making sure they are available and configured correctly within their DNS.
...And finally
2. What's www.domain.com/something.html? Well you now know what a subdomain is so
http://www.domain.com/ is the FQDN. If you've noticed, the FQDN goes from .COM which is
general, to WWW which is specific, so we've been reading the FQDN from Right to Left to
find the address of the correct
server. This is like getting to a street address. Com.=State, DOMAIN=street,
WWW=YOURHOUSE.
Well, once you've gotten to the door what do you do? Well, we usually want to see
what's inside, so for that, we begin to read from left to right again starting after the
.COM/ Anything after the .COM/ is either a directory,
web
page or file that can be access via a web browser or
ftp.
So, SOMETHING.HTML is actually the web page
document usually saved in Hyper Text Markup Language.
Did you get all that?
Date: June 12, 2001
From: NoClue
Hey...I couldn't let that one die. That post was the thing that started Peter and me
thinking about the '101' section in the first place.
Thanks for adding the links and updating it.
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