One of the best features of the Odoo framework is that we can extend Odoo and write our own modules without having to modify any of the Odoo source code. Instead, the changes we make are all contained in their own directory and their own files.
The primary advantage of this is that when Odoo modifies its source code with patches or bug fixes, we do not have to worry about our changes getting overwritten. Also, while we may still need to modify our code if Odoo makes a dramatic change to its source code, there is a reasonable chance that the changes required will be minimal.