What is new is the global reach, and global compatibility, of the internet. The internet is so named because it is an interconnection of networks. It connects small groups to form a single large group. The mechanism is more properly called 'online communication' or 'online messaging'. We will call it 'online communication', and by that term we mean sending and receiving electronic mail and making and looking at web pages.
Online communication is enticingly similar to things that have existed for a century.
It's a bit like a telephone call, a bit like a letter, a bit like a magazine or newspaper. The truth is that it's not very much like any of them. Online communication is not like any medium that has ever existed before, and trying to fully understand it by analogy will not work. But it is instructive to look at specific ways that online communication differs from earlier media.