A rupture disc is like a tiny little balloon that is made to pop when it gets too full. It's used in places where really important stuff is happening, like in a factory or in a big machine.
Let's say you have a big tank that holds something really dangerous like chemicals or gas. You need to make sure that the tank doesn't get too full and explode, right? That's where the rupture disc comes in!
The rupture disc sits at the bottom of the tank and it's made out of a thin piece of metal or plastic. When the pressure inside the tank gets too high, the metal or plastic of the rupture disc can't take it anymore and it breaks open.
When it breaks open, it lets out some of the pressure, kind of like letting a little bit of air out of a balloon. This keeps the tank from getting too full and exploding.
So the rupture disc is like a really important safety guard that protects people and things from danger.