DOSC TWiki snapshot as of mid-2005
When you use a computer on a network, all of the information sent over that network travels in little chunks of data known as "packets".
Now, just like a person at the PostOffice? who could set up a camera and record all of the information on postcards as they flow past, a PacketSniffer records a copy of all of the packets that travel across the network. Using this tool, one can determine a password that you send (if you don't encrypt it before you send it).