What is it?
Stacks are not exactly a data structure in itself, but a way of managing data inside a built data structure. It can be implemented with both Arrays and Linked Lists, or any other data structure, once it’s an abstract data structure.
Working with stacks mean that one cannot handle data that’s not on top of the stack. To retrieve data which was inserted first, one must first unstack the rest of the data. Data which was inserted last, is more easily retrieved.
The FILO principle
Stacks work with the FILO principle, which stands for First In, Last Out. This means that the first data inserted in the stack, will be the last to be retrieved.
How to implement a stack?
We can easily implement a stack structure when working with singly Linked Lists, because of the nature of its structure. If we only apply element insertion and removal at the top of the list, a stack structure will be characterized.