What are Protocol Buffers and why does gRPC use them?

Protocol Buffers (protobuf) are Google's language-neutral, platform-neutral, extensible mechanism for serializing structured data. gRPC uses protobuf for several reasons:

• Efficiency: Binary serialization is faster and more compact than JSON/XML
• Type Safety: Strongly typed schema prevents runtime errors
• Code Generation: Automatically generates client and server code
• Language Agnostic: Works across different programming languages
• Schema Evolution: Supports backward and forward compatibility

Example protobuf definition:

syntax = "proto3";

message User {
  int32 id = 1;
  string name = 2;
  string email = 3;
}

service UserService {
  rpc GetUser(UserRequest) returns (User);
}