As before, we will use an example to help explain the concepts. One of the great things about Odoo is being able to pick any existing application or module and add, on top of it, those extra features you need. So we are going to continue improving our to-do modules, and in no time they will form a fully featured application!

It is a good practice to split Odoo applications into several smaller modules, each of them responsible for specific features. This reduces overall complexity and makes them easier to maintain and upgrade to later Odoo versions. The problem of having to install all these individual modules can be solved by providing an app module packaging all those features, through its dependencies. To illustrate this approach we will be implementing the additional features using new to-do modules.