HTML and CSS Reference
The .com, .org, and .net TLD designations are currently used on the honor system,
which means that an individual who owns a shoe store (not related to networking) can
Country Code Top-Level Domain Names. Two-character country codes have also
been assigned as top-level domain names. These were originally intended to be mean-
ingful and relate the domain name country code to the geographical location of the
individual or organization that registered the name. In practice, it is fairly easy to
obtain a domain name with a country code TLD that is not local to the registrant. See
http://register.com and many other domain name registration companies for examples.
Table 1.2 lists some popular country codes used on the Web.
Table 1.2 Country codes
European Union (a group of countries rather than a single country)
The IANA Web site at http://www.iana.org/cctld/cctld-whois.htm has a complete list.
Domain names with country codes are often used for municipalities, schools, and com-
munity colleges in the United States. The domain name www.harper.cc.il.us denotes the
United States, Illinois, community college, Harper, and the Web server named www as
the site for William Rainey Harper College in Illinois.
The DNS associates domain names with IP addresses. The following happens each time
a new URL is typed into a Web browser:
1. The DNS is accessed.
2. The corresponding IP address is obtained and returned to the Web browser.
3. The Web browser sends an HTTP request to the destination computer with the
corresponding IP address.
4. The HTTP request is received by the Web server.
5. The necessary files are located and sent by HTTP responses to the Web browser.
6. The Web browser renders and displays the Web page and associated files.
The next time you wonder why it's taking so long to display a Web page, think about
all of the processing that goes on behind the scenes.
Markup languages consist of sets of directions that tell the browser software (and other
user agents such as mobile phones) how to display and manage a Web document. These
directions are usually called tags and perform functions such as displaying graphics, for-
matting text, and referencing hyperlinks.