Booleans

A boolean is a value that can only ever be one of two things: True or False. In Python, these keywords are always capitalized — unlike many other languages where they're written lowercase — and they represent the type bool.

is_raining = True
is_sunny = False
print(type(is_raining))  # <class 'bool'>

Booleans usually come from comparisons, like checking whether one number is greater than another. Python's comparison operators — ==, !=, <, >, <=, >= — always produce a bool result.

age = 20
print(age >= 18)   # True
print(age == 21)   # False

Every value in Python has a kind of built-in truthiness, even values that aren't actually booleans. When a value is used somewhere a True/False answer is needed (like an if statement), Python converts it automatically. Values that count as False are called falsy: the number 0, an empty string "", the special value None, and empty collections like an empty list []. Essentially every other value — including any nonzero number and any non-empty string — is truthy.

if "":
    print("this will not print")

if "hello":
    print("this will print")  # non-empty strings are truthy

In Python, the two boolean values are written ____, always with a capital letter, unlike lowercase true/false in some other languages.

Which of these values is considered falsy in Python?

An empty list, [], is considered falsy in Python.