Understanding habits, states, and familiarity.
Use this to talk about things that happened repeatedly in the past but do not happen now, or states that are no longer true.
Note: In questions and negatives, we usually use "did use to" (e.g., "Did you use to play soccer?").
Use this when you are accustomed to something. It isn't strange or new to you anymore.
This describes the process of becoming familiar with something. It's the journey from "new" to "normal."