Appending means adding an element at the end of an existing data structure or sequence.
Array/List: In arrays or lists, appending involves adding elements at the end without disturbing their original positions.
Stack/Queue: Stacks and queues are data structures where appending is done at one end, either the top (stack) or rear (queue).
Concatenation refers to combining two or more sequences into a single sequence, often used for appending strings.