In computer displays and graphics, the ratio of the width of a picture or picture area to its height. For example, an aspect ratio of 2:1 indicates that the picture is twice as wide as it is high. The aspect ratio is an important factor in maintaining correct proportions when a picture is incorporated into another document such as a Web page. In a multiuser or network environment, the process by which the system validates a user's logon information. A user's name and password are compared against an authorized list, and, if the system detects a match, access is granted to the extent specified in the permission list for that user. (Common Gateway Interface) A standard method of extending Web server functionality by executing programs or scripts on a Web server in response to Web browser requests. A common use of CGI is in form processing, where the Web browser sends form data to a CGI script on the server. A form field that can be selected by clicking a box. When a box is selected, it is usually displayed with a check mark or X. Check boxes are usually grouped to represent a set of non-exclusive choices. See also radio button.