1. Making a connection
Before we describe packet switching, it is useful to understand what it means to make a connection.
In the diagram below, the yellow device wants to make a connection to the red device over a local network or the internet.
One solution would be to have a permanent physical cable connecting one to another, like this:
This might be practical for a small local area network with only a few nodes. But it wouldn't work for a large network such as a WAN where millions of computers want to communicate randomly with each other.
The telephone system solved this connection problem with 'circuit switching'.