Peer to peer networks
Peer-to-peer is an efficient way of sending large files like TV programmes from one computer to another.
Normally when you download something from the internet, there are two computers involved.
The first is a big computer, say somewhere like the BBC, and the second is your computer at home.
When you download something the big computer sends it direct to your computer where it is stored to watch later.
But when the files are very large, like a TV programme, and everyone wants a copy at the same time, things can grind to a halt.
Peer-to-peer is different. It works much faster because it connects everyone's computer together and lets them send on programmes to people who are waiting.
All this is done completely automatically by your computer; it just means the programmes arrive much quicker.