Electronic mail, most commonly referred to as email or e-mail since approximately 1993, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks.
Some early email systems required that the author and the recipient both be online at the same time, in common with instant messaging. Today’s email systems are based on a store-and-forward model.
Email servers accept, forward, deliver and store messages. Historically, the term electronic mail was used generically for any electronic document transmission.
For example, several writers in the early 1970s used the term to describe fax document transmission. As a result, it is difficult to find the first citation for the use of the term with the more specific meaning it has today.