Electronic mail, most commonly called email or e-mail since around 1993
E-mail is one of the most widely used forms of communication today.
E-mail is faster and cheaper than traditional postal mail, but at least when you seal that envelope and stick a stamp on it, you can have some confidence that only the intended recipient will open it.
With e-mail, however, your message could be intercepted midstream, and you might never realize it. You have to take steps to secure and protect your e-mail messages.