What is Additive increase/multiplicative decrease?

The additive-increase/multiplicative-decrease algorithm is a feedback control algorithm best known for its use in TCP congestion control. AIMD combines linear growth of the congestion window when there is no congestion with an exponential reduction when congestion is detected. Multiple flows using AIMD congestion control will eventually converge to an equal usage of a shared link. The related schemes of multiplicative-increase/multiplicative-decrease and additive-increase/additive-decrease do not reach stability.