AWS’ ELB has 3 types: ALBs (Application Load Balancers), NLBs (Network Load Balancers) and Classic Load Balancers.
This diagram shows the basic components.
A Listener is a process that checks for connection requests based on the protocol and port you configure. Supported are:
Protocols: HTTP, HTTPS
Ports: 1- 65535
The rules defined for a listener set up how the LB routes requests to the targets in the target groups.