Can you put money on a step card at a store?

Excuse me, I was wondering if you could clarify something for me. I've heard about step cards, and I'm curious if it's possible to add funds to one of those cards at a store? I'm not entirely sure what a step card is, but I'm assuming it's some sort of prepaid card that can be used for purchases. Is that correct? And if so, would I be able to go to any store that sells these cards and add money to it, or are there specific stores or locations where I can do that? Thank you for your help.