URL and Domain Name system:
URL stands for Uniform Resource Locator. The URL specifies the Internet address of the file stored on a host computer connected to the Internet. Every file on Internet, no matter what its access protocol, has a unique URL. Web browsers use the URL to retrieve the file from the host computer and the specific directory in which it resides. This file is downloaded to the user's computer and displayed on the monitor connected to the machine.
URL's are translated in to numeric addresses using the Domain Name System (DNS). The DNS is a worldwide system of servers that stores pointers to web sites. The numeric address, called the IP (Internet Protocol) address, is actually the "real" URL.
Since the numeric strings are difficult for humans to use, alphanumeric addresses are employed by end users. Once the translation is made by the DNS, the browser can contact the web server and ask for a specific file located on its site.
