Channel Management Systems have been developed during the last few years in order to improve the hotel’s Reservation Department’s operation and accelerate its online presence.
A hotel Channel Manager is a system that updates the availability and rates of a hotel directly to major OTAs and retrieves reservations accordingly, making it easy for the hotel to offer its rooms online, avoiding overbooking and rate parity issues.
Source: What is a hotel Channel Manager and why hotels should use it?