Why Server-Sent Events (SSE) Exist

When developers need real-time updates, the first instinct is usually simple: “Let’s just ask the server every few seconds.” This approach is called polling. At first, it works fine. But as your application grows, problems start appearing: Too many unnecessary requests Increased server load Delayed updates Wasted bandwidth And suddenly, something that looked simple becomes inefficient. 🚨 The Problem with Polling Let’s say you're building a food delivery tracker. Your frontend keeps asking: Client → “Any update?” Server → “No” Client → “Any update?” Server → “No” Client → “Any update?” Server → “Order is out for delivery” This continues every few seconds. Even when there is no update, the request still happens. Now imagine: 10,000 users Each sending requests every 5 seconds That’s 120,000 requests per minute — most of them useless. 💡 What We Actually Want Instead of repeatedly asking: “Any update?” We want the browser to say: “Tell me when there is an update.” This flips the model com