The transport layer in TCP/IP networks sits below the application layer (that is, TCP sits just below HTTP) and above the internet layer (that is, TCP sits above Internet Protocol (IP)). The two possibilities are either Transmission Control Protocol (TCP), defined by RFC 793, or User Datagram Protocol (UDP), defined by RFC 768. The main difference between these two is that TCP is slower, but provides reliable transport, in that there is a packet sequencing control aspect not present in UDP. UDP, on the other hand, although not considered reliable, is faster.
Secure Sockets Layer (SSL) was first introduced in the early 1990s by Netscape as a way to secure communications between browser and server (see RFC 8446 for more details). Its goal was to provide privacy and data integrity to secure transport (such as TCP). Version 1.0 was never published, but version 2.0 was first made available in 1995, followed a year later by version 3.0, defined...
