Final answer:
A stack is a data structure with restricted access, operating on a Last In, First Out principle, commonly used in managing function calls, expression evaluation, and syntax parsing in computing.
Step-by-step explanation:
A stack is a list where access is restricted to the beginning (or top) of the list. Items are placed on the list at the top and can only be removed from the top. In computer science, this structure follows the Last In, First Out (LIFO) principle, where the last element added to the stack is the first one to be removed. This behavior is analogous to a stack of plates; you can only take the top plate to use it, and when you put it back, it becomes the top plate again.
Stacks are commonly used in various computing tasks such as managing function calls in a program's execution, expression evaluation, and syntax parsing. For instance, a stack could be used to track the sequence of function calls an application makes, so when a function is completed, the system knows which function to return to.