ITCH is a direct data-feed protocol such as TCP (Transmission Control Protocol) or UDP (User Datagram Protocol). ITCH makes it possible for subscribers to track the status of each order from the time it is first entered until the time it is either executed or canceled. Subscribers can also disseminate or receive administrative messages. ITCH is intended for information exchange only. Active trading is supported by the OUCH protocol and other related protocols, such as OTTO and RASHport.
According to a representative of the NASDAQ, neither "ITCH" nor "OUCH" stand for anything.