When designing for a screen, for instance the UI of a product, the choices of and possibilities of how to approach this process are nearly endless with new tools popping up every day.
You could of course always start to directly build the interface with code, but this usually requires quite a lot of skill, time and effort – especially if you decide to change something on the way. The more suitable approach is to design the interface first in a lower fidelity and increase the level of detail on the way when needed.
A Comprehensive Guide To Wireframing And Prototyping - Smashing Magazine
Atomic Design Methodology | Atomic Design by Brad Frost