A stack may refer to any of the following:
1. In computer networking, a stack is a frequently used method of describing TCP/IP.
2. In computer programming, a stack is a special data structure that removes items in the reverse order from which they were added.
3. A stack may also refer to a collection of computers that are stacked upon each other or a series of caseless computer components a computer farm.
4. In some video games, multiple players join to defeat a creature, creating a party or raid. When fighting some creatures, it is necessary to stack together. When players stack, they are moving to a common spot, standing in a tight group to create a smaller target for the creature to hit or to share incoming damage.
5. Stacks are a collection of folders found on the far right-hand side of the Apple dock. The three default stacks are Applications, Documents, and Downloads.