Variables of type Boolean have two possible values: True and False. These are not strings, but Python keywords.

b = True
print(type(b)) # bool
s = "True"
print(type(s)) # str

Inputs can be cast to type bool, but be aware that strings "False" and "0" are cast to true. The only string that is cast to false is the empty string. Casting from ints to bools, 0 is the only falsy int.

s = "0"     # string "0"
n = int(s)  # int 0
b = bool(n) # bool False