What does full duplex connection actually mean?

Question

I am trying to understand why websocket protocol is faster than http. Some of the points that I came across were that 1) because the overhead of headers is handshake is reduces by ensuring minimum headers 2) websockets maintain a full duplex connection with the server (meaning they can send and receive data simultaneously)

I don't quite get the second point. I only get jargon on the internet. Can someone explain what having a true duplex connection means?

Answer 1

It means support for data transmission between two points in both directions at exactly the same time. As opposed to half duplex, or to simplex.