A stack is usually described as a linear data structure, and this is because of how it works. With stack, when retrieving data, the data that entered last will be the first to be retrieved. This is because it follows the "last in first out" principle. To understand this better, think of a stack as a container with an opening, the last item to be added to the container will always be the first to be retrieved or deleted.
When inserting data into the stack, the operation is called "push," and it is called "pop" when retrieving or deleting the data. In contrast, a queue uses a different principle entirely. In the queue, the first element to be added will be the first to be retrieved or deleted.
Elements are usually inserted from the rear, and they will be retrieved from the other side, which is the front. The principle used in the queue is "first in first out."