Electronic mail, or Email, is the term used to describe the tool which allows one computer user to send a message to one or more other computer user over a computer network in a digital form. Email can be sent internally to members of an organisation through their internal computer network or theye can be sent externally to anyone in the world by using the network of computers world wide that make up the internet. It is very similar to our traditional mail system with post boxes, post offices, envelopes and addresses.
Email can be as quick and convenient as a phone call.
The recipient does not have to be connected for you to send them a message. They can connect at a later time and read and respond to your message when it suits them. When you post a message or letter to somebody via conventional mail, the letter is passed from one post office to another until it arrives at a post office close to its eventual destination. It is then delivered to that person's mail box. Email works in a very similar way.