HTTP is a synchronous protocol. A client sends a request and waits for a response. This works well for operations that complete in milliseconds — a database read, a record update, a validation check. It breaks down for operations that take seconds, minutes, or longer: video transcoding, report generation, bulk data exports, machine learning inference on large inputs, email campaigns to millions of recipients.

Holding an HTTP connection open for a minute or more is technically possible and practically wrong. Clients time out. Load balancers have maximum request durations. Users cannot tell the difference between a server still working and a server that silently failed. Long synchronous operations produce brittle integrations and poor user experiences.

Every integration eventually confronts the same question: how does my system learn that something changed in someone else’s system? The two answers are polling and webhooks. Polling asks the question repeatedly. Webhooks get notified when the answer changes. Understanding which approach fits a given situation — and why — shapes everything from latency and cost to reliability and operational complexity.

Polling: The Default That Mostly Works

Polling is the simpler mental model. Your application sends requests to an API on a schedule — every 30 seconds, every minute, every hour — and checks whether anything has changed since the last check. If yes, process the changes. If no, wait for the next interval.