Aldis uses a lock on their shopping carts that you insert a quarter into to unlock it. Then after you’re done, you lock the cart back up, and it gives you your quarter back.
(Since it’s your first time: Be aware that Aldis doesn’t bag your groceries for you. They don’t even offer free shopping bags, although they usually have some you can buy. Best to bring your own bags.)
Good things to know ahead of time.