The stack is a common system for managing the order events resolve in. It is used as the foundation of event resolution in Magic: the Gathering and many other games.
Based on the data structure of the same name, the stack is a system for organizing the resolution of actions in many games where players have the ability to "react" to events in a way that the response resolves before the initial event, e.g. magic-the-gathering.
The main characteristic of the stack is it's last-in first-out (LIFO) property.