Architecture of Apache-Tomcat connectivity,port number and protocol

We often follow a server configuration without understanding its concept and how it works.
This practice would bring you a problem. for example, if any problem occure related to it, you can't figure out the real/root cause...
Only when you know how it works, you can check steps what you have configured and what it is supposed to be, again otherwise you will never find a problem cause.

Connector List(Apache<==>Tomcat)