The key to accessing all this information is the URI - the Uniform Resource Identifier. Each web page has a unique address, specified by its URL, which tells the client/browser how to access the page. See the Wikipedia entry for URI.
Take, for example:
http://student.cs.ucc.ie/cs1050/index.html
Example 2.1. The parts of a URL
http:
the method of “delivery” (ftp, file, etc.) Secure
sites use https, an encrypted form on HTTP. The
:// is important to
distinguish this from the server name that follows
student.cs.ucc.ie:
the server computer the document is stored on. This could
also be referred to by its “dotted-quad” IP number,
e.g. 143.239.116.100. Breaking
this down further:
student
the “hostname” — the name of the individual computer/server. These are usually decided upon by the organisation concerned, and can seem quite random!
cs
the “Department” - cs (Computer Science)
ucc
the Organisation - ucc (domain name = ucc.ie)
ie
the “country code” -
uk,
fr,
de, etc. (there's no code for
USA) - for more details see the Country Codes FAQ
cs1050:
the directory/folder
index.html:
the file itself
The slashes (/) are used to separate the
parts of the address, in the same way as file locations use backslashes on your
own PC. So, for example,
C:\Documents and Settings\gbstring\My Documents\website\hello.html
is equivalent to
file:///c:/Documents%20and%20Settings/gbstring/My%20Documents/website/hello.html
where %20 represents a space character. Note
that spaces in filenames work well in Microsoft Windows, but don't work at all
well with many webservers.
There're a couple of other features of this address that you may come across
elsewhere on the web. The “hostname” here is
student.cs.ucc.ie, but I've also set up an
ALIAS which points the name
cosmos to this server, so that we can use
http://cosmos.ucc.ie/cs1050/index.html
to refer to the same page. An alias is defined by your ISP in the DNS (Domain Name System) records, so has to be set up by them.
There's also a REDIRECT for the default page, i.e. if no page is given in the address, then the webserver will automatically add the /index.html file path to the page. Try typing
http://cosmos.ucc.ie/
and see what happens.