Communication between Ignition gateway and clients

A customer wants to understand how the communication between Ignition gateway and its client takes place. During discussion, he mentioned may terms likes http, TCP/IP, TCP/IP socket etc. I do not know the minute differences between them.

Can anyone explain where these terms fit in from Ignition gateway and client communication point of view? Are there any security measures other than SSL that needs to taken for ensuring secure communication?

Thanks in advance.

To enhance security in Ignition, you may opt to enable SSL encryption. This will affect all communication to and from the Gateway that is done over the HTTP protocol. This includes not only browsers interacting with the Gateway's web interface, but all Vision Client communication as well.

(Source: https://docs.inductiveautomation.com/display/DOC80/Gateway+Common+Tasks)

Thank you witman for you reply.

You're welcome @Neo. An additional thought; you asked:

Per manual quote posted previously, SSL should secure all Vision Client <-> Gateway communication, however, depending on locations of clients and gateway, requiring a secure VPN for the connection (network setup, not Ignition config) is another possible layer of security.