If you’ve been following stories like the Snowdon NSA revelations or the recent Silk Road bust, you’ll probably have come across mentions of Tor. Want to know exactly what it is? The Next Web does an excellent job of both explaining Tor, and putting it in context:

When users installed Tor software onto their computers, it would conceal their identity and network activity from anyone spying on their behavior. This was accomplished by separating the identification and routing information. The data is transmitted through multiple computers via a network of relays run by like-minded volunteers — almost like how users installed SETI software to look for extraterrestrial beings.