Differences Between Domain Names and URLs
We sometimes use the terms URL and domain name interchangeably, but they are, in fact, different. A URL (uniform resource locator) is the computer information that directs your browser to show you a specific document on the internet in a specific way. A domain name can be part of the URL, and exists for the convenience of human users. A domain name relies on DNS (domain name servers) to "translate" the name to its physical IP (internet protocol) address.
The URL instructs your browser exactly where to go and what to do when it gets there using a specific protocol, server, and document. The most common protocol is "http://", (hypertext transfer protocol), or "https://" if the document is on a secure server. Another common protocol is ftp (file transfer protocol). Next comes the server ID (which can be a domain name), followed by the specific document or page.
Domain Name Significance
Computers don't need domain names, people do. Associating a specific server with a name that's easy to remember simplifies Internet navigation for us. It's much easier to remember Company.com than a server name, and simplifies the job for the website provider as well. Domain names are controlled by a handful of companies, known as registrars, appointed by ICANN (Internet Corporation for Assigned Names and Numbers), and domain names are held in a master database maintained by InterNIC (Internet Network Information Center). You obtain a domain name by applying for it through a registrar and paying a fee.
Domain Name History
"Top-level domain" refers to the ".com," ".org," ".net" and ".edu" part of a URL. These were the original top-level domains, with .com the most popular. Additional top-level domains, such as .biz, .us and .info have been added, as well as domains such as .uk, .fr or .ja which designate entities within specific countries.
Examples of Domain Names
Some well-known domain names: microsoft.com (software maker Microsoft Corp.), earthlink.net (Earthlink, provider of website, email and other Internet services) and harvard.edu (Harvard University).
Examples of URLs
URLs at the above domains include http://office.microsoft.com/en-us/default.aspx (the default page for Microsoft's Office software, for the US market, in English), http://www.law.harvard.edu/academics/curriculum/index.html (Harvard University's main page discussing curriculum at their Law School), and https://webmail.earthlink.net/wam/login.jsp?redirect=%2Fwam%2Findex.jsp&x=-1176621850&x=-2008600187 (the login page for Earthlink's online email service). Note all the strange numbers and characters in this URL -- these are additional computer instructions.