We created a new module from the start, covering the most frequently used elements in a module: models, the three base types of views (form, list, and search), business logic in model methods, and access security.
In the process, you got familiar with the module development process, which involves module upgrades and application server restarts to make the gradual changes effective in Odoo.
Always remember, when adding model fields, an upgrade is needed. When changing Python code, including the manifest file, a restart is needed. When changing XML or CSV files, an upgrade is needed; also when in doubt, do both: upgrade the modules and restart the server.
In the next chapter, you will learn about building modules that stack on existing ones ...