In computer networks, rate limiting is used to control the rate of traffic sent or received on a network interface. Traffic that is less than or equal to the specified rate is sent, whereas traffic that exceeds the rate is dropped or delayed. A device that performs rate limiting is a rate limiter.

Rate limiting is performed by policing (discarding excess packets), queuing (delaying packets in transit) or congestion control (manipulating the protocol’s congestion mechanism). Policing and queuing can be applied to any network protocol. Congestion control can only be applied to protocols with congestion control mechanisms, such as the transmission control protocol (TCP).