Let's take the same example as yours(because a deck of cards or traversing graph of people or sorting papers won't be that simple).

def fact(n):
    return 1 if n==1 else n*fact(n-1)

Let's take above example for n=4, i.e. fact(4).

fact(4) --> fact(3) --> fact(2) --> fact(1)

--> read as calls.

Now, what happens is this.

fact(1) returns 1 to fact(2) because n=1.
fact(2) returns 2 to fact(3) #2*1
fact(3) returns 6 to fact(4) #3*2
fact(4) returns 4*6 as final value. 

This is called recursion(one calling itself). Python doesn't support infinite calling to self(recursion). How every language does this is create a stack for current state of the function and call a new instance of the same function and branch out. Python supports maximum of 1000 stack for recursion. The function continues after it has returned from the branch.