Long Polling: How the Web Solved Real-Time Messaging Before WebSockets

Traditional HTTP polling, where browsers repeatedly ask servers for updates, created massive infrastructure strain as platforms scaled — with up to 98% of requests returning no new data. Engineers around 2008 faced a crisis when increasing poll frequency to once per second generated hundreds of thousands of empty server responses every minute. Long polling emerged as a smarter alternative, where the client sends a request and the server holds the connection open until new data is actually available. Once the server responds with fresh information, the client immediately reconnects and waits again, creating a near-instant experience without the overhead of constant empty replies. This approach reused standard HTTP infrastructure while fundamentally shifting the communication model from repeated client-side asking to server-side event-driven notification.