agreement ： Rules established for data exchange in a computer network 、 A set of standards or conventions .
- UDP( It can be compared to texting , I'm texting you , You can turn it off , This number may not exist )
- Facing connectionless , Data is not secure , Fast . Do not distinguish between client and server .
- Connection oriented （ Three handshakes ）, Data security , It's a little slow . Divided into client and server .
- Three handshakes ： The client first requests the server , The server responds to the request , To transmit data .