Stacks are a core computer science idea: they’re a way of organizing data so that the most recently added item is the first one you take out, like a stack of plates.

Simple definition

  • A stack is a data structure that stores elements in a line, where you only add and remove from one end, called the “top.”
  • It follows the Last-In, First-Out (LIFO) rule: the last thing you put on the stack is the first thing you get back.

Core operations

  • Push : Add an element to the top of the stack.
  • Pop : Remove the element from the top of the stack (and usually return it).
  • Peek/Top : Look at the top element without removing it.
  • Many implementations also offer checks like isEmpty and size to see if the stack has elements and how many.

Everyday analogy

  • Imagine a stack of plates in a cafeteria: you put clean plates on top, and when someone needs a plate, they take the top one.
  • You cannot easily pull out a plate from the middle without disturbing others, just like a stack only lets you safely work at the top.

Where stacks are used

  • Function calls and recursion : Programming languages use a call stack to track which function is running and where to return when it finishes.
  • Undo history : Text editors and many apps use stacks to implement undo, pushing each change onto a stack of actions.
  • Expression evaluation and parsing : Compilers and calculators use stacks to evaluate expressions and manage nested structures like parentheses.

“Stack” beyond data structures

  • In broader tech talk, a “tech stack” can mean a set of technologies that work together (for example, a web stack like LAMP).
  • In all these uses, the idea is still that multiple related components are organized in layers or in an ordered collection, even if it’s not a strict LIFO structure.

Information gathered from public forums or data available on the internet and portrayed here.