How to Read Web Addresses

Top Level Domain

The last part of a Web Address (the letters at the far right) is called the "top-level domain." In the case of networksolutions.com, the top-level domain is .com. The following is a list of top-level domains and the organizations they signify.

.COM
Designed for commercial entities. .com rapidly became the top-level domain for business. Today, anyone can register a Web Address in the .com domain.

.NET
Designed for organizations directly involved in Internet operations, such as
network providers and network operation centers. Today, anyone can register in
the .net domain.

.ORG
Designed for miscellaneous organizations, including non-profit groups. Today,
anyone can register in the .org domain.

.EDU
Two- and four-year, accredited colleges and universities

.GOV
US Federal Government entities

.MIL
US military

Country Codes
Other top-level domains include those for countries (CA for Canada, UK for the
United Kingdom, HK for Hong Kong, etc.), which are based on the
International Standards Organization's 3166 standard for country abbreviations.

Second Level Domain

To the left of the top-level domain is what is called the "second-level domain." In networksolutions.com, "networksolutions" represents a second-level domain within the top-level domain of .com. Using whitehouse.gov as another example, "whitehouse" is the second-level domain within the .gov top-level domain.

Sub-Domains

It is possible to have sub-domains. Sub-domains would appear to the left of the second-level domain. For example, a company using the Web Address raincoats.com might create a sub-domain called southern.raincoats.com to represent the southern division of their company.

These various levels mean that the Domain Name System is hierarchical. In
fact, it is often compared to an inverted tree, with the root ("dot") at the top,
branches (the top-level domains) stemming from the root, and the second-level
domains beneath each branch representing "nodes" on the branches.

Web Addresses are an essential part of the Internet

Web Addresses play an essential role in allowing people to easily use the Internet. You will find Web Addresses everywhere, from e-mail addresses to Web sites. For example, almost every e-mail address looks something like this:

Userid@domain_name

Uniform Resource Locator

 On the Web, Web Addresses play an important role in Uniform Resource Locators, or "URLs." URLs are part of a standardized addressing scheme for Internet resources, and they help users locate these resources by indicating exactly where they are. A URL identifies a particular Internet resource; for example, a Web page, gopher server, library catalog, image or text file.

The basic structure of a URL is hierarchical. Unlike the hierarchy of a Web Address (which is read from right to left), the hierarchy of a URL moves from left to right:

protocol://subdomain.second-level-domain.
top-level-domain:port/directory/filename

Actually, since the combination of the sub-domain(s), second-level domain, and top-level domain is simply called the "Domain Name," (commonly known as a Web Address) let's just rewrite our example as:

protocol://domain-name:port/directory/filename

Here are a few real-life examples of URLs:

http://www.healthyway.com:8080/exercise/mtbike.html
gopher://gopher.state.edu/
ftp://ftp.company.com/

Take another look at "http", "gopher", and "ftp" in the above examples. The first part of a URL ("protocol://") specifies the type of resource to be accessed and the protocol to be used to transmit the resource.

This portion of the URL actually serves as a set of instructions for your computer and the network, telling them how to make the connection and get the information.

For example, the letters "http" stand for "hypertext transfer protocol," the method used to transfer information on the World Wide Web.

Here are a few of the other protocols used in URLs:

Protocol—Internet Tool Invoked

ftp—File Transfer Protocol
news—Internet News Protocol (Usenet)
gopher—Gopher
telnet—telnet
http—HyperText Transfer Protocol