Create complex conditions with logical operators (and, or, not)

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Sometimes a single condition isn't enough to make a decision. You might want to check whether two things are both true, or whether at least one of them is true. For example, you might need to verify if an account is both active and funded, or if a user is either an admin or a moderator.

Python's logical operators let you combine multiple conditions into one expression.

The three logical operators

Operator	What it does	Example	Result
and	True only if both sides are True	True and False	False
or	True if at least one side is True	True or False	True
not	Flips a Boolean value	not True	False

Using and (all conditions must be met)

Use and when all conditions must be met to run a block of code:

age = 20
has_ticket = True

if age >= 18 and has_ticket:
    print("Entry granted.")
else:
    print("Entry denied.")

Output:

Entry granted.

Using or (at least one condition must be met)

Use or when any one condition is enough to run a block of code. In everyday language, usually "or" means "one or the other, but not both." However, in Python, "or" means "one or the other, or both."

is_weekend = False
is_holiday = True

if is_weekend or is_holiday:
    print("The office is closed.")

Output:

The office is closed.

Using not (reverse a condition)

The not operator reverses a Boolean value. If the condition is True, it becomes False, and vice versa. This operator is useful when you want to check for the absence of a condition.

is_logged_in = False

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

Output:

Please log in to continue.

Combining operators

You can combine and, or, and not in a single expression. Always use parentheses to group conditions and make your code easier to read:

score = 85
has_extra_credit = True
is_past_due = False

# Example: Pass if (Score is high OR extra credit is earned) AND the work isn't late
if (score >= 90 or has_extra_credit) and not is_past_due:
    print("Requirement met.")

Avoid shortcut errors

When comparing a single variable against multiple values, you might be tempted to write something like this:

# Incorrect: This code will not work as intended
if score == 90 or 100:
    print("You got an A!")

In this case, Python evaluates score == 90 first, which is either True or False. Then it evaluates 100, which is always True. Nonzero numbers and nonempty strings always count as True in Python. As a result, the condition is always True, regardless of the value of score. Always compare each value explicitly:

# Correct: Each value is compared explicitly
if score == 90 or score == 100:
    print("You got an A!")