Carnivore is a surveillance technology, a software program housed in a computer unit, which is installed by properly authorized FBI agents on a particular Internet Service Provider’s (ISP) network. The Carnivore software system is used together with a tap on the ISP’s network to “intercept, filter, seize and decipher digital communications on the Internet”. The system is described as a “specialized network analyzer” that works by “sniffing” a network and copying and storing a warranted subset of its traffic. In the FBI’s own words “Carnivore chews on all data on the network, but it only actually eats the information authorized by a court order”. This article, in two parts, will provide an overview of the FBI’s Carnivore electronic surveillance system. The Carnivore software’s evolution, its ‘prey’ and the system’s relationship with Internet Service Providers will be the focus of the study. (Although the FBI’s Carnivore surveillance system is now officially called DCS1000, as the surveillance system is more commonly referred to as “Carnivore”, that term will be used throughout). Also addressed in the article are misconceptions about Carnivore, publicly available sniffer programs, Carnivore’s functionality, methods to counter Carnivore as well as the software’s limitations. In addition, the pertinent American law allowing for wiretapping and electronic surveillance as well as programs and policies outside the United States regarding electronic surveillance are surveyed, and an overview of ECHELON, the global interception and relay system, is provided. The aim is to provide the paper’s readers with a better understanding of these surveillance systems: naturally, only through an in-depth knowledge can the benefits and dangers they present for the public (government), private (individual communications users) and technical industry (ISPs) be understood. [Copyright &y& Elsevier]