Every API starts with a choice that will shape every decision that follows: what protocol are you building on? REST, GraphQL, and gRPC are the three dominant options in modern API development, and none of them is universally correct. Each reflects a different set of assumptions about who is calling the API, how often, and what they need back.

Understanding the tradeoffs is not optional knowledge for serious API developers. It is the foundation.

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.