Main (quick) concepts
This page is about the first things that would take lots of time to figure out.
If you read Flask documentation you will learn different ways to do things. The first ones you will meet are usually quite easy, but usually not good practices for real projects.
But then while you keep reading after your first code experiments, you will encounter more complex patterns that will lead you 99% of the time to modify your initial code to stick with these concepts below.
To make things work from the beginning, we will just see them now, in minutes. So we will take for granted that they are actually the best configuration for your needs.