Booleans (True/False).

In Python, a Boolean (or bool) is a fundamental data type that represents one of two possible states: True or False.

Think of it like a light switch—it is either on or off. Booleans are the foundation of logic in programming. They allow your code to make decisions, compare values, and control the flow of your program.

Important Note: In Python, Booleans are case-sensitive. They must always start with a capital letter (True and False). Using lowercase true or false will result in an error.

Here are 10 examples showing how Booleans work and how they are used in Python:

1. Direct Assignment

You can assign a Boolean value directly to a variable to track a state or condition.

Python

is_logged_in = True
has_errors = False

print(is_logged_in)  # Output: True

2. Equality Operator (==)

Comparing two values using == evaluates whether they are the same, resulting in a Boolean.

Python

user_guess = 5
correct_answer = 5

print(user_guess == correct_answer)  # Output: True

3. Mathematical Comparisons (>, <)

Using operators like greater than (>), less than (<), or greater than/equal to (>=) always returns a Boolean.

Python

temperature = 30

print(temperature > 100)  # Output: False

4. Logical and

The and operator checks if both conditions are true. If even one is false, the whole statement is false.

Python

has_ticket = True
is_vip = False

print(has_ticket and is_vip)  # Output: False

5. Logical or

The or operator checks if at least one condition is true.

Python

is_weekend = True
is_holiday = False

print(is_weekend or is_holiday)  # Output: True

6. Logical not

The not operator reverses the Boolean value. True becomes False, and False becomes True.

Python

is_raining = False

print(not is_raining)  # Output: True

7. Evaluating Numbers (Truthy/Falsy)

You can use the bool() function to evaluate any Python object. For numbers, 0 is always False, and any other number (positive or negative) is True.

Python

print(bool(1))    # Output: True
print(bool(0))    # Output: False
print(bool(-42))  # Output: True

8. Evaluating Strings and Collections

For strings, lists, or dictionaries, empty ones are False, and ones with content are True.

Python

print(bool("Hello"))  # Output: True
print(bool(""))       # Output: False (empty string)
print(bool([]))       # Output: False (empty list)

9. The Membership Operator (in)

You can check if a specific item exists inside a string, list, or other collection. This check returns a Boolean.

Python

vowels = ['a', 'e', 'i', 'o', 'u']

print('a' in vowels)  # Output: True
print('z' in vowels)  # Output: False

10. Using Booleans in Conditional Statements

Booleans are most commonly used to control if statements. The code indented under the if block only runs if the condition evaluates to True.

Python

battery_level = 15

# battery_level < 20 evaluates to True, so the print statement runs
if battery_level < 20:
    print("Please charge your device!")