Stacks and queues are both essential data structures in computer science, but they operate on different principles and serve different purposes. A stack follows the LIFO (Last In, First Out) principle, meaning the last element added is the first one removed. This structure is used in scenarios where you need to backtrack or undo an operation. A common example is the call stack in programming languages. When a function is invoked, its execution context is placed on the stack. Once it completes, the function's context is removed. Similarly, stacks are used for algorithms like Depth-First Search (DFS), where you explore as deeply as possible before backtracking. Queues, on the other hand, follow the FIFO (First In, First Out) principle, meaning the first element added is the first one removed. This is more like a real-life queue at a checkout counter. The person who arrives first is served first. Queues are used in scenarios where tasks need to be processed in order, such as in breadth-first search (BFS) algorithms, task scheduling, or managing resources in a round-robin fashion. One common use of queues is in printer task management, where print jobs are handled in the order they are received. The key difference between stacks and queues lies in how they manage the order of operations. Stacks are ideal when the order of operations needs to be reversed or undone, while queues are better for situations where operations need to be processed in the order they arrive. Both data structures have constant time complexity O(1) for their core operations (push/pop for stacks, enqueue/dequeue for queues), making them efficient choices depending on the task at hand.