HTML and CSS Reference
In-Depth Information
The
how
is specified by the protocol (for example, HTTP). Slashes and other characters are
used to separate the parts of the address into machine-readable pieces. The basic structure
of the URL is shown here:
protocol://site address/directory/filename#fragmentid
The next several sections look at the individual pieces of a URL in closer detail.
Server Address
A document exists on some serving computer somewhere on the global Internet or within a
private intranet. The first step in finding a document is to identify its server. This may be
performed by a site's IP address,
http://10.0.0.1
though it is more likely that an alphanumeric domain name is employed,
http://www.htmlref.com
The name may be fully qualified with a machine name, a domain, an organization type,
and potentially, a country code. For example,
http://www.htmlref.com
would specify the name of a machine called “www” in the domain htmlref, which is in the
top-level COM domain. By contrast,
http://dev.htmlref.com
would reference a machine known as “dev” in the same domain.
Very often for primary Web sites within a domain the machine name is omitted, so we
simply write
http://htmlref.com
However, such configuration is up to the owner of the domain. This short-hand form
should be employed as most sites are reachable without a www prefix.
Historically, top-level domains such as those found in Table D-1 are used.
T
ABLE
D-1 Common
Top-Level Domains
Domain
Intended Type
.com
Commercial entities
.net
Networks
.edu
Educational institutions
.org
Non-Profit organizations
.gov
Government entities
.mil
U.S. military
