Long polling is a server push communication technique used to simulate real-time interaction over HTTP, particularly in web applications without WebSocket or HTTP/2 support. It involves the client sending a request to the server, which keeps the connection open until new data becomes available or a timeout occurs, after which the client immediately re-initiates the request cycle. This method is beneficial for responsive applications like chat apps and multiplayer games, as it reduces perceived request frequency and improves real-time data flow. However, long polling can incur HTTP overhead and requires robust error handling and optimization strategies, such as batching responses, compression, caching, and connection pooling, to enhance performance and scalability. While long polling shares similarities with WebSockets and Server-Sent Events (SSE), it differs in that it supports bidirectional communication and necessitates periodic reconnection. Various programming languages and frameworks, including JavaScript, PHP, Python, Ruby, Java, and .NET/C#, support long polling, and it can be further optimized using cloud-native solutions or services like PubNub, which abstracts scalability and infrastructure complexities.