Modern web development requires realtime experiences and communication between users and servers. WebSocket is a protocol that allows full-duplex two-way communication over a single TCP connection. React applications can use WebSockets to receive updates and notifications without delay, with components subscribing to WebSocket events and updating the UI in response to incoming data or events. Alternatives to WebSockets include HTTP long polling, Server-sent events (SSE), and WebRTC. This article explores top WebSocket libraries for React applications, including React useWebSocket, Socket.IO, SockJS Client, and WS, along with their pros, cons, and use cases. Factors to consider when choosing a WebSocket library include project requirements, library limitations, React compatibility, and community support.