What do casinos do with inactive accounts? And what does inactivity mean - not logging in to your casino account or logging in say every two months without playing any game?

I also learned that there is something called a dormancy fee or maintenance charges on those inactive accounts which covers for administrative cost incurred by those accounts. I learned that the deduction is from the remaining balance in the account. What about inactive accounts without any balance? On the other hand, what type of fee is charged on an active account?