API throttling is the practice of controlling the rate at which applications can make requests to an API (Application Programming Interface). It is essential for maintaining service quality and preventing system overload by managing the number of requests from users or applications per specified time. Throttling helps ensure fair usage among clients, enhances server performance, and protects against abusive behavior that could lead to outages. API throttling is particularly important in high-traffic environments, allowing developers to maintain an efficient and stable service while delivering a positive user experience.