ECHELON is a name used in global media and in popular culture to describe a signals intelligence collection and analysis network operated on behalf of the five signatory states to the UKUSA agreement; Australia, Canada, New Zealand, the United Kingdom and the United States, known as AUSCANZUKUS.

The system has been reported in a number of public sources, first in a New Statesman article entitled Someone's Listening in 1988. Its capabilities and political implications were later investigated by a committee of the European Parliament published in 2001.

In its report, the European Parliament states that the term ECHELON is used in a number of contexts, but that the evidence presented indicates that it was the name for a signals intelligence collection system. The report concludes that, on the basis of evidence presented, ECHELON was capable of interception and content inspection of telephone calls, fax, e-mail and other data traffic globally through the interception of communication bearers including satellite transmission, public switched telephone networks and microwave links. The committee further concluded that "the technical capabilities of the system are probably not nearly as extensive as some sections of the media had assumed".