Wireless Protected Access, Version 2 (WPA2) is the version of Wi-Fi security used in most cases today. This diagram illustrates the general layout of the security data used by WPA2. There’s a new version coming out, WPA3, but it doesn’t seem to be in any products yet.

I put this diagram together several years ago for my textbook. I recently performed a web search for similar diagrams only to realize that there aren’t any posted.