while loop

while loop iterates when condition is True until condition is False or when immediate break statement inside the loop body is run.

a=0
while a<5:
    print(a)
    a+=1

or calculate Fibonacci series

a, b = 0, 1
fib=[]
while True:
#    print(a)
    if len(fib)>=10:
        break
    else:
        fib.append(a)
    a, b = b, a+b 
    print(fib[-1], end=" ")