A Universal (or Uniform) Resource Locator is a character string a program uses to connect to an Internet resource, such as a Web page or email address. In addition to a basic address, such as "amazon.com," the URL may include a data token that a Web server uses to identify you or your session. This allows the server to deliver more sophisticated, consistent and customized information.
A URL has several parts, including the access method and the server, domain and page names. For example, in the URL "news.yahoo.com/business" the access method is Hypertext Transport Protocol, also known as HTTP, the server name is "news," and the domain is "yahoo.com." The name following the slash indicates Yahoo News' business page. If a question mark follows a page name, as in "news.google.com/nwshp?hl=en&tab=wn," the items that follow the page "nwshp" are parameters Google uses to display the news. For example, "hl=en" sets the page's language to English. Web programmers may place information for dozens of parameters in a URL, so when you click on a link, the Web server receives the information. Tokens are data automatically generated by a Web server and passed as parameters in URLs.
Many sites, including forums, banks, news outlets and retailers, have dynamic Web pages that reconfigure themselves to provide you with personalized information. These sites use programs that produce Web pages as their output. The programs receive information passed to them in URL parameters, decode the parameters and generate Web pages based on this information.
Instead of serving up a page, a Web program may send your browser to a different site or page without your having to click a link. For example, if an organization revamps its site, a page that you bookmarked may display a message informing you of the change, then tells you it will send you to a new page in five seconds. Web developers call this process "redirection," and among other uses, it allows different sites to pass Web users to different cooperating sites automatically. If you log into one Web site and it sends your browser to another one, the first site may put a token in its URL.
URL tokens are a way to give users access permission for various Web resources. When you log into a Web site with a user ID and password, that information gives you access to the site. If the site's owner has an agreement with another site, the first site may give you access to information hosted on the second site. The first site sends a request for an authentication token to the second site's Web server. The server generates a security code and passes it to the first site. The first site redirects your browser to the second site using the token in the URL. Your browser logs into the second site automatically using the token. This lets you view the second site without the additional step of logging into it.