## Introduction
HTTP is not the only protocol. There are other protocols for communication.
### TCP
TCP: Transmission Control Protocol
### Characteristics
- Packets arrive in order
- Data Integrity (no missing packet)
### UDP
UDP: User datagram protocol
- No data integrity guarantee
- Packets may not arrive in order
### RPC
[gRPC](https://grpc.io/): open source high performance Remote Procedure Call
### Characteristics
- Strick Protocol to Follow
- TCP and UDP's data can be of any form
## Reference
- [System Design Primer (Communication)](https://github.com/donnemartin/system-design-primer#communication)
- [Computer Networks - a system approach (PDF)](https://cseweb.ucsd.edu/classes/wi19/cse124-a/courseoverview/compnetworks.pdf)
- [Computer Networks - a system approach (Doc Style)](https://book.systemsapproach.org/)