API rate limiting protects backend services from being overwhelmed by too many requests. Token bucket algorithms allow short bursts while enforcing a long-term average rate. Sliding window counters track request counts over a rolling time interval rather than fixed buckets. Rate limit headers inform clients how many requests remain and when the limit resets. Exponential backoff retries failed requests with increasing delays to reduce thundering-herd effects. Circuit breakers stop sending requests to an unhealthy service until it recovers, preventing cascade failures.
