Society and communication

People have always needed to send messages. In order, the main ways are: a messenger who carries a spoken or written message, the post, the telegraph that sends signals along a wire, the telephone that carries a voice, radio and television that broadcast to many, the mobile phone that goes with a person, and the internet that joins most of these in one network. Each step made messages faster, or reached more people, or both. We can describe communication in two ways. By number of people: one-to-one (a phone call between two people), one-to-many (a teacher speaking to a class, or a message to a group) and mass communication (a broadcast to a very large audience). By timing: synchronous, when both sides take part at the same moment, as in a call; and asynchronous, when the receiver answers later, as with a letter or an e-mail. The internet can do all of these, so we choose by need: an urgent question suits a call, while a long report suits an e-mail that can be read when ready.