The process of forwarding visitors from one Web page to another is called redirection. Depending on the programming method used, redirection usually occurs before the requested page is loaded into the Web browser. It is possible to organize the redirection so that the visitor sees a message screen at the old address informing of the redirect with a countdown until the redirection will occur.
The main reason for redirects is to compensate for when a Web page moves. A Web address is called a Uniform Resource Locator, or URL. The address contains many elements, including the domain name (the site name) a path and the name of the file containing the page. If the website changes its name, then all the links to all the pages on that site will become dead links. If the website is reorganized and pages get moved from one directory to another, then the links to those pages will break. If any part of the name of the file containing a page changes, then all links pointing to that page will break. Redirects resolve this problem.
Without redirects, many links on the Web would return a “page not found” error. Links on a Web page are references, not connections. The link records an address and clicking on the link causes the associated address to be copied into the browser’s address field. This triggers the browser to go and fetch that page from the given address. If the page is not still at exactly the same address, the user is presented with an error message. This wastes time, because the user will then have to search to find the page he’s looking for, or one like it. This is bad news for a website - which may lose visitors to rival sites that are easier to access.
Another reason website administrators create redirects is to consolidate many domain names on to one site. The “.com” part of a domain name is called the domain, and some websites own as many permutations of their site name as possible, including all the domains relevant to their home country or target market. Rather than maintain many copies of the same site, the administrator redirects all the pages that mirror the pages on the main site through to their real counterpart.
Although most redirects are organized by the website, there are other causes for a sudden, unexpected redirect. If the page you land on is nothing like one you expected, then your browser is probably being controlled by a trojan, or a virus. One trojan that particularly attaches itself to Firefox browsers hides itself as an add-on. Add-ons are extra programs downloaded onto the computer to enhance the capabilities of the browser. The trojan uses the names of legitimate add-ons to escape detection. Another trojan, called Win32/Alureon, hides itself as a printer driver. Both redirect users to pages of their choice.