Simple representation of a stack runtime with push and pop operations. Additionally, a peek operation may give access to the top without modifying the stack. The name “stack” for this type of structure comes from the analogy to a set of physical items stacked on top of each other, which makes it easy to take an item off the top of the stacks and queues in data structures pdf, while getting to an item deeper in the stack may require taking off multiple other items first. Considered as a linear data structure, or more abstractly a sequential collection, the push and pop operations occur only at one end of the structure, referred to as the top of the stack.
This makes it possible to implement a stack as a singly linked list and a pointer to the top element. A stack may be implemented to have a bounded capacity. If the stack is full and does not contain enough space to accept an entity to be pushed, the stack is then considered to be in an overflow state.