Partie 8 — Conditional Statements in Python (if, elif, else) – Complete Beginner Guide 2026

Learn how to use if, elif, and else in Python with clear examples. Understand conditional logic, comparison operators, nested conditions, and real-world use cases step by step.

8. Conditional Statements (if, elif, else)

Conditional statements allow your Python program to make decisions. Instead of running code from top to bottom without thinking, conditions allow the program to choose different actions based on data.

Main Idea: Conditions control the flow of your program.

1) The Basic if Statement

The if statement runs a block of code only if the condition is True.

age = 20

if age >= 18:
    print("You are an adult.")

If the condition age >= 18 is True, Python executes the indented block. If it is False, nothing happens.

2) Using else

The else block runs when the if condition is False.

age = 16

if age >= 18:
    print("You are an adult.")
else:
    print("You are a minor.")

The program always executes one of the blocks.

3) Using elif (Multiple Conditions)

The elif statement allows you to check multiple conditions.

score = 75

if score >= 90:
    print("Excellent")
elif score >= 70:
    print("Good")
elif score >= 50:
    print("Pass")
else:
    print("Fail")

Python checks conditions from top to bottom. Once it finds a True condition, it stops checking.

4) Comparison Operators in Conditions

Conditions use comparison operators:

== Equal to
!= Not equal to
> Greater than
< Less than
>= Greater or equal
<= Less or equal

number = 10

if number == 10:
    print("Number is exactly 10")

5) Logical Operators in Conditions

You can combine multiple conditions using logical operators.

age = 25
has_id = True

if age >= 18 and has_id:
    print("Access granted")

and → both conditions must be True
or → at least one condition must be True
not → reverses the condition

6) Nested Conditions

You can place an if inside another if.

age = 20
is_member = True

if age >= 18:
    if is_member:
        print("Discount applied")
    else:
        print("No membership discount")

Avoid too many nested conditions. It can make your code harder to read.

7) Short Conditional (Ternary Operator)

Python allows short conditions in one line.

age = 20
message = "Adult" if age >= 18 else "Minor"
print(message)

8) Common Beginner Mistakes

Using = instead of ==
Indentation errors
Forgetting to convert input to int()
Incorrect logical operator usage

Always test different values to verify your conditions work correctly.

Conclusion

Conditional statements are fundamental in Python programming. They allow your applications to respond dynamically to user input, system state, and data values.

Mastering if, elif, and else prepares you for more advanced logic such as loops, functions, and real-world application development.

Practice writing small decision-based programs to strengthen your understanding.