2600: The Hacker Quarterly is an American seasonal publication of technical information and articles, many of which are written and submitted by the readership, on a variety of subjects including hacking, telephone switching systems, Internet protocols and services, as well as general news concerning the computer "underground."

Phreaking is a slang term coined to describe the activity of a culture of people who study, experiment with, or explore telecommunication systems, such as equipment and systems connected to public telephone networks. The term phreak is a sensational spelling of the word freak with the ph- from phone, and may also refer to the use of various audio frequencies to manipulate a phone system. Phreak, phreaker, or phone phreak are names used for and by individuals who participate in phreaking.