|In computer programming, a stack is a container that holds other variables (much like an array). However, whereas an array lets you access and modify elements in any order you wish, a stack is more limited. The operations that can be performed on a stack are identical to the ones above:|
1) Look at the top item on the stack (usually done via a function called top())
2) Take the top item off of the stack (done via a function called pop())
3) Put a new item on top of the stack (done via a function called push())
A stack is a last-in, first-out (LIFO) structure. The last item pushed onto the stack will be the first item popped off. If you put a new plate on top of the stack, anybody who takes a plate from the stack will take the plate you just pushed on first. Last on, first off. As items are pushed onto a stack, the stack grows larger — as items are popped off, the stack grows smaller.