Namespace Basics

Hi, I'm a total beginner trying to understand the basics of naming folders. I understand that in the data folder you can name a subfolder anything for a namespace, and if you don't it will default to the "minecraft" namespace. My question is, what should I be using for a namespace for these folders in the data folder. Is it kind of like categorizing sections of my datapack? How do y'all name for subfolders in the data folder? If I'm starting out with learning how to make custom structures, should I name this folder "structures"?