What is the difference between the data structures 'stack' and 'queue'?

Stack — a data structure that operates on the LIFO (Last-In, First-Out) principle. The last added element will be the first to be retrieved.

Queue — a data structure that operates on the FIFO (First-In, First-Out) principle. The first added element will be the first to be retrieved.

Main operations and their implementation:

Operation	Stack	Queue
Add	push (to the end)	enqueue (to the end)
Remove	pop (from the end)	dequeue (from the front)
View	peek (last)	peek (first)
Empty?	is_empty	is_empty
Size	size	size

Examples of usage:

• Stack: Browser history (back button), function call management (call stack), syntax analysis.
• Queue: Task scheduler in the operating system, buffers in networks, processing requests in order.

Implementation in Python:

# Stack: can use a list
stack = []
stack.append(1) # push
stack.append(2)
item = stack.pop() # pop

# Queue: recommended to use collections.deque
from collections import deque
queue = deque()
queue.append(1) # enqueue
queue.append(2)
item = queue.popleft() # dequeue