A very, very simplistic view of Packet Switching.

Basically data is split into separate packet. Each Packet can then be send via a different root.

Each packet contains extra data to say where it is going and the order it should arrive in as well as some verifying data

For more information about Packet Switching see:-
Packet Switching. How devices communicate.
http://www.acomputerportal.com/devices.html