Electronic mail, or as it is more commonly called email or e-mail, is a method of exchanging digital messages. It true to say that e-mail is an essential part of most business and personal communications.

E-mail systems are based on a store-and-forward model in which an e-mail server accepts delivery of e-mail from a client, stores it in a temporary file and then forwards it to the next relay server in the chain or deliver it directly to the end reciptient. Originally, e-mail was always transmitted directly from one user's device to another's; nowadays this is rarely the case

An electronic mail message consists of two components, the message header, and the message body.

The message header contains control information, including, minimally, an originator's email address and one or more recipient addresses. Usually additional information is added, such as a subject header field, relay server information and more often than not spam score information. The message body is essentially the message content.

Originally a text-only, email was extended to carry multi-media content attachments, which were standardized in with RFC 2045 through RFC 2049, collectively called, Multipurpose Internet Mail Extensions (MIME).

The foundation for today's global Internet e-mail service was created in the early 1970’s by ARPANET and standards for encoding of messages were proposed as early as 1973 (RFC 561). An e-mail sent in the early 1970s looked very similar to one sent on the Internet today. Conversion from the ARPANET to the Internet in the early 1980s produced the core of the current service.

Network-based e-mail was initially exchanged on the ARPANET in extensions to the File Transfer Protocol (FTP), but is today carried by the Simple Mail Transfer Protocol (SMTP), first published as Internet standard  (RFC 821/RFC2821) in 1982. In the process of transporting e-mail messages between systems, SMTP communicates delivery parameters using a message envelope separately from the message (header and body) itself.