Table stakes

Only the chips in front of you when a hand starts can play in it, so nobody can bet you out of a pot.

Example

Ben bets 100 and you have 30 left: you can call all in for 30, and the 70 you cannot match goes back to Ben.

Related

Practise it in 5 minutes The pot & all in, a short free lesson.

Quads is for adults, 18 and over. It teaches with play chips only: there is no real money, ever.