As a data structure, the stack can only be inserted and deleted at one end. It stores data according to the principle of first in and then out. The first data entered is pushed to the bottom of the stack, and the last data is at the top of the stack. When data needs to be read, it pops up from the top of the stack (the last data is read first). So the input sequence of a stack is 12345, and only one output sequence of the stack is 5432 1.
Extended data:
In a computer system, the stack has a dynamic storage area. Programs can push data onto the stack or pop data from the top of the stack. In the i386 machine, the top of the stack is located by a register called esp. The operation of pushing the stack reduces the address of the top of the stack, and the operation of ejecting the stack increases the address of the top of the stack.
Stack plays an important role in program running. Stack can be used to store breakpoints in function calls, which is used in recursion. Most importantly, the stack stores the maintenance information needed when a function is called, which is usually called stack frame or activity record.