When to create new apps in django -

i've tried reading few things before asking, when should new apps created in django?

for instance, have website domain scanner have registration/login/etc?

should functionalities login , registration (2) separate apps?

what best practices in order determine if new app should created in django?

excuse newbieness, tried searching , reading this before asking

but couldn't concrete explanation of best practices this.

here login , registration make account app. upto you, how want fragment whole site. use intuition.