Evaluate conditions with Booleans and comparison operators

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Before a program can make a decision, it needs a way to ask a question and get a yes or no answer. Python answers this kind of question with Boolean values and comparison operators.

Boolean values

A Boolean (labeled as bool) is a data type that has exactly two possible values: True or False. These two values are the building blocks of all decision-making in Python.

is_game_over = True
is_user_logged_in = False

print(type(is_game_over))  # Output: <class 'bool'>

Note

Python is case-sensitive. The Boolean values True and False must be capitalized exactly as shown. If you write true or false, Python treats them as undefined variables and raises a NameError.

Comparison operators

Comparison operators compare two values and return a Boolean result:

Operator	Meaning	Example	Result
==	Equal to	5 == 5	True
!=	Not equal to	5 != 3	True
>	Greater than	10 > 3	True
<	Less than	3 < 10	True
>=	Greater than or equal to	5 >= 5	True
<=	Less than or equal to	4 <= 3	False

For example:

score = 85
print(score >= 90)  # Output: False
print(score >= 70)  # Output: True

Comparing strings

Comparison operators also work with strings. You can check if two strings are equal, or compare them alphabetically:

entered_password = "secret123"
correct_password = "secret123"

print(entered_password == correct_password)  # Output: True

Equality and assignment

Be careful not to confuse the equality operator (==) with the assignment operator (=).

• Single equals (=) is for Assignment: It assigns the value on the right to the variable on the left.
• Double equals (==) is for Comparison: It checks if the two values are equal and returns a Boolean result.

Observe what happens if you accidentally use a single equals sign in a comparison:

score = 100

# Trying to check if score equals 50, but accidentally resetting it:
print(score = 50)

Output:

TypeError: 'score' is an invalid keyword argument for this function

Remember to use == when you want to compare values, and = when you want to assign a value to a variable.