Code Generator & Invitation Code

Hi,

Could you help me to better understand about the usage of this 2 apps?

1) Invitation Code
2) Code Generator
A sample of usage scenario.

Is it use at the Joomla backend only or any user we assign at front end can use it?

For Code Generator, in the description it say "With the codes, you can then use it for offline marketing or other promotional material that can be used to reward the user."

How is that work?


Thanks for any help