Rate limiting is a technique used in computer networks to control the amount of incoming and outgoing traffic to or from a server. By setting a maximum number of requests a user can make in a specific time frame, it helps prevent abuse and ensures fair usage among all users. This is particularly important for services like APIs that may experience high demand. Implementing rate limiting can protect servers from overload and potential crashes caused by excessive requests. It also enhances security by mitigating risks such as DDoS attacks, where attackers flood a server with traffic to disrupt its normal operations.