🧠 The Core Problem

In traditional web systems (HTTP 1.1), communication is client-initiated:

• The client (browser/app) sends a request.
• The server responds and closes the connection.

So, if the server gets new data (like a new chat message), it cannot push it to the client directly.

The client has to keep checking:

“Hey server, do you have something new for me?”

That’s where Polling comes in.

🔁 What is Polling?

✅ Simple Polling:

Client repeatedly sends HTTP requests every few seconds:

Client → Server: Any new message?
Server → Client: Nope.
(3 seconds later…)
Client → Server: Any new message?
Server → Client: Yes, here’s one.

❌ Problem:

• Most of the time, the server replies “no new data”.
• Wastes bandwidth and server CPU.
• High latency (client might get message 2–3 seconds late depending on interval).

⚡ What is Short Polling?