system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: The Joker card in a playing card deck

Where does it originate? What's its purpose?
gpt
Well it is actually used in some lesser played card games, and it's sometimes used in variants of some more common games as a wildcard meaning it can represent any card you like.

In casual home card games is also frequently used to 'replace' a lost card so you don't have to buy a new deck. E.g. if you lose or damage the Queen of Hearts, say, you can just write the name of the card on the joker and use that in the deck as a replacement, keeping the deck usable for a little longer.

Finally, most of the big playing card manufacturers such as the United State Playing Card Company use it (or at least one of the jokers) as a guarantee card. If you have a defective deck you just send back the guarantee card and a defective card and they send you a whole new deck. This not only saves on your shipping but seeing as you only have one guarantee card it makes sure that you can't get 52 new decks from one defective pack by sending the cards back one at a time.