about:

about:

The about: option, without any argument, displays a web page like about screen. Although much of the information on this page is identical to the Firefox About box (accessed by selecting Help, About in the menu), the formatting is different. This screen contains a bit more information.

Figure 9.1 shows the results of about: in Firefox version 1.0.4. Other versions of Firefox might have slightly different information.

Figure 9.1. about: gives product version information and the browser identification string, which is sent to the web server when a page is requested.

All browsers will send a string to the server telling the server of the type of browser. Virtually all reference Mozilla (even Internet Explorer) as a browser standard.