ITCH is the ultra-low latency protocol for accessing Real Time Market Data. ITCH has been developed to maximize performance and so meet the requirements of latency sensitive trading strategies. For latency arbitrage this best electronic protocol. For latency arbitrage and HFT, this is one of the fastest methods to get quotes, but at the same time the most expensive.
Connecting via ITCH protocol makes it possible to get quotes directly from the exchange without losing speed and with the maximum possible frequency of data acquisition (1000 updates per second or more).