Submit listing then login/register

1. What comes first registration or login?
2. What is login and registration called?

What comes first registration or login?

Registration only happens the first time you access the system. It is a way to check your credentials. Every time after your initial registration, you will log on to the system using the username and password you created.

What is login and registration called?

Sort of like "authentication", but that's really more specific to the login part. The next best I can come up with is "onboarding", but that really applies more to the register part.