The codename for the NSA's (
National Security Agency) high-tech information-interception system. Echelon has a collection of satellite dishes (supposedly Echelon is made up of a network of satellite dishes)overseas, basically in all english-speaking countries (including America, Canada, England, Australia, and New Zealand...).
Echelon is said to intercept, on a daily basis, billions of e-mails, phonecalls, downloads, satellite transmissions, faxes, and any other form of
digital media. This is used to help locate possible terrorists in the new age of cyber warfare.
Echelon was made popular, and positively (as in, in a good way), by Tom Clancy's
Splinter Cell. ^_^