Stack Visualization

Trace some operations on an empty stack: Push $3$: stack is $[3]$

Push $7$: stack is $[3, 7]$

Push $1$: stack is $[3, 7, 1]$

Pop: returns $1$, stack is $[3, 7]$

Peek: returns $7$, stack stays $[3, 7]$

Pop: returns $7$, stack is $[3]$

The rightmost element is the "top." The last element you added is the first one you remove.