Why we need "custom_addins directory" for customizing modules?

Question

I am confused about why we need to make a custom_addons directory, however we already have addons directory in files. I downloaded odoo 13 (windows).

Answer 1

Mostly to make a separation between multiple code bases, for example, keeping Odoo provided addons directory separate from your customized addons directory. Let's say you want to use addons from multiple third party repositories, you can keep each repositories code base in separate directory and add the paths in addons_path in odoo.conf file.