As the others says the toolkit rules are apperently the ones for beginners. The stack is apperently one of the things people find most confusing in Magic (and the stack is just a metaphysical temporary object, so it is not exactly wrong to put it like that)
It's not temporary. It's a game zone that always exists, one single stack from deal to defeat. It is oftentimes empty (as often are other zones, like graveyard or exile), but it still exists, non-temporarily.