Polling vs SSE vs WebSockets | Real-Time Communication Explained | System Design #HLD

Polling vs Server-Sent Events vs WebSockets — Complete Guide to Real-Time Communication How do applications like WhatsApp, Instagram, stock trading apps, live notifications, and real-time dashboards receive updates instantly? In this video, we understand the different techniques used for real-time communication between clients and servers. We'll cover Short Polling, Long Polling, Server-Sent Events (SSE), and WebSockets from scratch and understand how they work internally. In this video, you'll learn: What is Polling? What is Short Polling? How Short Polling works Problems with Short Polling What is Long Polling? How Long Polling works Short Polling vs Long Polling What is Server-Sent Events (SSE)? How SSE works internally How the client establishes an SSE connection SSE communication format One-way communication in SSE What is a WebSocket? How WebSocket connections work WebSocket Handshake Full-duplex communication WebSocket vs HTTP Connection management Scaling WebSocket servers Load Balancers and persistent connections Polling vs SSE vs WebSockets When should you use each approach? Real-world use cases Polling vs SSE vs WebSockets In this video, we compare all these communication methods based on: Communication Direction | Connection Type | Latency | Server Load | Scalability | Complexity | Real-Time Capability | Use Cases You'll understand when to use: Short Polling for simple periodic updates Long Polling when immediate updates are needed without persistent bidirectional connections Server-Sent Events (SSE) for server-to-client real-time updates WebSockets for real-time bidirectional communication This video is part of my System Design / HLD Series, where we learn the fundamental concepts required to design scalable real-world systems and prepare for System Design and Software Engineering interviews. If you're learning System Design, Backend Development, Distributed Systems, or Real-Time Communication, this video will give you a strong foundation. Connect With Me Instagram:   / themonkeystalk   LinkedIn:   / mayank888k   Subscribe for more videos on System Design, DSA, AI, Software Engineering and Interview Preparation. Topics Covered Polling | Short Polling | Long Polling | SSE | Server-Sent Events | WebSockets | Real-Time Communication | System Design | HLD | Distributed Systems #SystemDesign #HLD #WebSockets #SSE #Polling #LongPolling #ShortPolling #RealTimeCommunication #BackendDevelopment #DistributedSystems #SoftwareEngineering