Contrary to what you would expect from its name, Transport Layer Security (https://en.wikipedia.org/wiki/Transport_Layer_Security) does not concern the TCP (Transmission Control Protocol) layer of the TCP/IP protocol stack. Instead, TLS in this context applies to the application (https://en.wikipedia.org/wiki/Application_layer) (top) layer. The data at this layer is transmitted using end-to-end encryption based on a secret which the sender and receiver share, thus ensuring the privacy of the communication. In addition, depending on how the protocol is configured, one or both sides can be authenticated, and a message integrity check can be enabled to ensure the reliability of the message.
Two protocols are used to ensure transport layer security: SSL (Secure Sockets Layer) and TLS . Of the two, only TLS should be used, and even at that, the later the version...