Slow down to avoid overload
During a sale, an online shop might slow down non-urgent reports so it can keep taking orders. This is throttling: reducing work when the system is busy.
Backpressure is when a busy part of a system tells another part to send it less work.
How it differs from rate limiting
Rate limiting sets an allowance, such as 100 requests a minute, and may reject any extra. Throttling can instead delay work or slow it further as demand rises. Teams should explain delays so people do not keep trying and add to the load.