What is CRDT (Conflict-free Replicated Data Type) and how does it apply to real-time collaboration?

CRDTs are data structures designed to be replicated across multiple nodes where updates can be made concurrently without coordination, and all replicas eventually converge to the same state — without requiring a central authority to resolve conflicts. Types: G-Counter (grow-only counter), LWW-Register (last-write-wins), RGA/LSEQ (ordered lists for collaborative text editing). In real-time collaborative applications (Google Docs, Figma, Notion), CRDTs enable offline editing — users can edit without a server connection, and changes merge deterministically when they reconnect. The Yjs library implements CRDT-based shared data types (Y.Text, Y.Map, Y.Array) and integrates with WebSocket providers (y-websocket) to sync state across clients. Unlike Operational Transformation (OT, used by Google Docs's older system), CRDTs don't require a central server to transform operations — all replicas can merge directly. Automerge is another popular CRDT library.