What is gRPC and how does it compare to REST?

gRPC is a high-performance RPC framework using Protocol Buffers (binary serialization) over HTTP/2. Features: strongly typed contracts (.proto files), code generation, bidirectional streaming, built-in deadline/cancellation. Advantages over REST: faster (binary, multiplexing), smaller payload, streaming support, better tooling for types. Disadvantages: harder to debug (binary), less browser support (requires grpc-web), steeper learning curve. Ideal for microservices, mobile backends, low-latency requirements.