Used tto and Did use to

A common mistake both for learners of English as well as native speakers is the difference between “Used to” and “Use to” and when (or if) we put the letter D at the end of the verb.
First let’s look at the meaning of it:
Used to = an action or habit that was common in the PAST but not anymore.
This should not be confused with
To be used to = accustomed to something (normally out of habit or experience)