Case Sensitive username Is craft's username field case sensitive when logging in?

I'm importing 80 users into the database and when emailing the users I want to be sure how this works so we don't hit issues when they all try to log in.

Many thanks
I've tested this locally on Craft3 and Craft2 and it seems that the username field is not case sensitive (e.g. admin, ADMIN, and AdMiN all worked equally as well for me).