TCP Congestion Control is a mechanism used in computer networks to manage data transmission and prevent network congestion. It adjusts the rate of data sent based on the current network conditions, ensuring that packets are transmitted efficiently without overwhelming the network. The process involves several algorithms, such as Slow Start, Congestion Avoidance, and Fast Recovery. These algorithms help to dynamically increase or decrease the transmission rate based on feedback from the network, allowing for smoother data flow and reducing the likelihood of packet loss due to congestion.