A stack refers to a linear collection of elements which, as a simple data structure in computer science, is used for storing a collection of elements with two principal operations: push, that puts an element into the collection, and pop, which removes the most recently added element. This last-in-first-out behavior suggests that the last element added to the stack will be the first one to be taken out.

Components of Stack

Elements:

The items or values that are stored in the stack are called elements. Elements are basically homogeneous, meaning they are usually of the same data type.

Top:

A pointer or an index pointing to the most recently added element in the stack. If the stack is empty then, top pointer is usually set to a special value say –1.
Capacity:

Maximum number of elements that the stack can hold: It can either be fixed in case of a static array implementation or dynamic in case of implementations by a dynamically resizing array or linked list. Operations on a Stack Push: This operation adds an element to the top of the stack. Before this, a check is made to ensure that the stack has not reached its capacity, thereby avoiding potential overflow. Algorithm Check if the stack is full.
Else, the top pointer is incremented.
The new element gets stored in the memory location which the top pointer points.

Pop:

Doesn’t take any arguments. Removes and returns the top element of the stack. Check in advance whether the stack is empty to avoid underflow.
Algorithm:
Check whether the stack is empty.
In case of not, return the element that is at the top pointer.
Decrement the top pointer by 1.

Peek or Top:

Returns the top element of the stack without removing it. This allows seeing what element is about to be added to the stack but not actually removed.
Algorithm:
Check whether the stack is empty.
In case of non-emptiness return the element according to the top pointer.

IsEmpty:
Checks if stack contains any elements.
Algorithm:
Return true if top pointer is – 1 or any other indication on emptiness.
Else return false.

IsFull:

Checks if stack has reached its maximum capacity.

Algorithm:
If the top pointer is equal to capacity minus one then return true otherwise return false. Implementation Types of Stacks Array Based Stack: Array of fixed size for storing elements. Pros: Easy and straight forward w.r.t implementation and efficient access. Cons: Capacity fixed and needs resizing if no. of elements cross the capacity declared at the beginning. Linked List-Based Stack: A linked list of nodes where every node holds an element and a pointer referring to the next node.
Pros: Varying in size; no capacity needs to be pre-defined. Cons: Marginally more complex to implement; greater memory overhead to store the pointers. Applications of Stacks Expression Evaluation Expression evaluation is one major application area of stacks. More specifically, expression parsing in postfix or prefix notation is implemented using stacks. Function Call Management In many programming languages, the call stack is the run-time stack that is used to manage function calls, local variables, and return addresses. Undo Mechanism:

Applications that require implementing undo and redo capabilities, such as text editors, use a stack where all the actions are pushed to the stack, and thus they can be undone by just popping the stack.

Syntax Parsing: Compilers and interpreters make use of stacks to parse and validate the syntax of expressions and statements.

Conclusion
The stack is a versatile and very powerful data structure with a number of applications in computing. It is particularly useful in situations where the last element added to the list has to be accessed first, because of its LIFO attribute. One needs to understand the basic operations and constituents that makeup a stack so that its power can be exploited fully in the design of algorithms and solution of problems.