A stack is a linear data structure that operates on the Last-In-First-Out (LIFO) principle, where the last element added to the stack is the first one to be removed. Stacks are used in many real-world and programming scenarios, such as expression evaluation (like converting infix expressions to postfix) and implementing backtracking algorithms (such as depth-first search in graphs). A stack can be thought of as a pile of plates, where you can only add or remove plates from the top. The two primary operations on a stack are `push`, which adds an element to the top of the stack, and `pop`, which removes the element from the top. Additionally, the `peek` operation allows you to look at the top element without removing it. In TypeScript, stacks can be implemented using arrays or linked lists. For example, you can `push` elements into an array and `pop` them from the array to mimic stack behavior. Stacks are widely used in function call management in programming languages, where each function call is pushed onto the stack, and once the function completes, it is popped off. Another common use of stacks is in undo-redo mechanisms, where the last action can be undone by popping it off the stack. Understanding stacks is important for solving problems related to recursion, expression evaluation, and memory management in programming.