True, False, and Comparisons

A boolean is one of exactly two values: True or False. They are the answers your program gives to yes-or-no questions, and almost every decision comes down to one.

Comparisons make booleans

Comparing two values produces a boolean. Notice that checking equality uses two equals signs, ==, because a single = already means "assign":

print(5 == 5)    # True   (are they equal?)
print(5 != 3)    # True   (are they different?)
print(5 > 3)     # True
print(5 < 3)     # False
print(5 >= 5)    # True   (greater than OR equal)
print(5 <= 4)    # False

You can store the result in a variable like any other value:

age = 20
is_adult = age >= 18
print(is_adult)   # True

Truthiness

Python also treats some everyday values as "truthy" or "falsy" when it needs a yes or no. The falsy ones are worth memorising: 0 (and 0.0), the empty containers ("", [], {}, (), and an empty set), None, and False itself. Almost everything else is truthy.

print(bool(0))      # False
print(bool(""))     # False
print(bool("hi"))   # True
print(bool(42))     # True

So an empty box counts as "no" and a filled one counts as "yes". That single idea powers a huge amount of real code.