Where to make put customisations

How does SuiteCRM V8’s customization framework differ from the V7 approach of replicating module components in the custom/ directory?

SuiteCRM V8 introduces a more modular and streamlined customization framework compared to the V7 approach.

In V8, customizations are handled through a modular extension framework. Developers can create specific extension files for various components.

This approach consolidates changes into a single compiled file during a “Repair and Rebuild” process, ensuring better performance and reducing conflicts between multiple customizations

This seems to be Front-end, my question is do we have anything relative to this question for the back-end?

Most of the back-end development listed here:

https://docs.suitecrm.com/developer/

Thank you I’ll take a good gander