6.4 TLS overview
The main task of the TLS protocol is to create a secure communication channel between two parties: server Alice and client Bob. The only thing that RFC 8446 assumes is a reliable, in-order data stream on the underlying transport layer. The two most widely used transport layer protocols are the Transport Control Protocol (TCP) and the User Datagram Protocol (UDP).
Thus, TCP lends itself to being a transport layer for TLS. In contrast, TLS doesn’t work with protocols such as UDP that provide no guarantees regarding message delivery or the sequence of the messages. There is, however, a closely related alternative to TLS called Datagram Transport Layer Security (DTLS), which works on top of UDP and offers similar security guarantees to TLS [149].
6.4.1 TLS terminology
RFC 8446 uses the following terms to specify TLS. A client is an endpoint that initiates a TLS connection. A server is an endpoint that receives the request from the client to establish a TLS connection...
