Logical Operators

Logical operators (and, or, not) combine Boolean expressions to create more powerful conditions. They are essential for writing programs that can handle complex real-world rules.

Simple comparisons can only check one thing at a time. But real decisions often involve multiple conditions — a rollercoaster might need you to be both tall enough and old enough. To combine conditions in Python, you use logical operators: and, or, and not.

The Three Logical Operators

Operator	Meaning	Result is True when...
`and`	Both conditions	Both sides are True
`or`	Either condition	At least one side is True
`not`	Opposite	The condition is False

The `and` Operator

and requires both conditions to be True for the overall result to be True:

age = 15
height = 140

if age >= 12 and height >= 130:
    print("You can ride!")
else:
    print("Sorry, you cannot ride.")

If either condition is False, the whole expression is False and the person cannot ride.

Truth table for and:

A	B	A and B
True	True	True
True	False	False
False	True	False
False	False	False

The `or` Operator

or only requires one condition to be True:

day = "Saturday"

if day == "Saturday" or day == "Sunday":
    print("Weekend! No school.")
else:
    print("Weekday. Time for school.")

Truth table for or:

A	B	A or B
True	True	True
True	False	True
False	True	True
False	False	False

Note

or is inclusive — it is True if one or both sides are True. In everyday English "or" sometimes implies "but not both", but in programming or always means "at least one".

The `not` Operator

not flips a Boolean value:

is_logged_in = False

if not is_logged_in:
    print("Please log in.")

not False is True, so the message displays. not True would be False.

Tip

not is useful for making conditions read more naturally. if not is_empty: is clearer than if is_empty == False:.

Combining Multiple Operators

You can combine and, or, and not in the same expression:

score = 85
is_member = True

if score >= 80 and is_member or score >= 95:
    print("Prize awarded!")

Warning

Be careful with operator precedence: not binds most tightly, then and, then or. Use brackets to make your intentions explicit and avoid subtle bugs: if (score >= 80 and is_member) or score >= 95: is much clearer.

A Practical Example

username = input("Username: ")
password = input("Password: ")

valid_user = username == "admin"
valid_pass = password == "secure99"

if valid_user and valid_pass:
    print("Access granted.")
elif valid_user and not valid_pass:
    print("Incorrect password.")
else:
    print("Unknown username.")

Practice Problems

What does this expression evaluate to? (5 > 3) and (10 < 8)

Show answer

False. The first part (5 > 3) is True, but the second part (10 < 8) is False. True and False evaluates to False.

Write a condition using logical operators that checks whether a number n is between 1 and 100 inclusive.

Show answer

n >= 1 and n <= 100. Both conditions must be True for the number to be in the valid range, so and is the correct operator.