What is composed of a user ID, "at" symbol, and name of the computer or Internet site for an email?

An email address is structured specifically to include a user ID, followed by the "@" symbol, and then the domain name of the email service provider or the Internet site where the email account is hosted. This format is crucial because it uniquely identifies the destination of the email. For example, in "username@example.com," "username" represents the user ID, and "example.com" denotes the Internet site associated with the email service.

Other options do not capture this exact format—while a website URL refers to the web address used to access a site, contact info encompasses various forms of communication details, and a username is simply a unique identification for a user that does not necessarily include the email's structure. Therefore, the composition of an email address distinctly highlights its function and necessity in digital communication.