HTML & CSS: The Good Parts

URIs

In a perfect system, Uniform Resource Identifiers, or URIs (formerly Uniform Resource Locators, or URLs) would be hidden from the site visitor. They aren’t especially human-readable, comprised as they are of a protocol token, a host alias, and something that looks like a filesystem reference but isn’t. URIs often end in token/value pairs that are deliberately designed to be computer-readable, as opposed to visitor-friendly.

We’re all familiar with simple URIs like http://www.example.com/ that point to the home page of a site. These appear in advertisements and on business cards, and the http:// has come to mean “type this in to find the website.” However, well-crafted URIs can contain a lot of information—look at commonly encountered URIs at your favorite search site or news site, and you’ll see a lot more going on. Google search result URIs, for example, can contain a parameter named start that specifies the number of results ranked higher than those displayed, as in http://www.google.com/?q=hypertext&hl=en&start=10. In a similar vein, popular Content Management System (CMS) platforms and e-commerce catalog platforms allow the same resource to be associated with multiple URIs, where the longer URIs enhance a resource’s searchability or specify that additional content be served along with the core resource (e.g., a product listing or the summary of a weblog entry).

Note

Browsers and other tools use the HTTP protocol to process URIs and retrieve information. If you want to know ...