1   What Is a Conditional?

Every day you make decisions based on conditions: if it is raining, take an umbrella. If the bus is full, walk instead. Programs do the same thing — they evaluate a condition, and depending on whether it is true or false, they follow a different path.

In Python, the main tool for making decisions is the <strong>if</strong> statement. Here is the simplest possible example:

temperature = 35

if temperature > 30:
    print("It is hot outside.")

Python evaluates the condition temperature > 30. Because 35 > 30 is True, it runs the indented line. If temperature were 20, the condition would be False and the print would be skipped entirely.

2   Comparison Operators

A condition is built from a comparison — a question about how two values relate to each other. Python gives you six comparison operators. Every comparison produces a boolean result: either True or False.

You can test any of these directly in Python, and Python will simply print True or False:

print(10 > 7)    # True
print(5 == 6)    # False
print(3 != 3)    # False
print(8 >= 8)    # True

2.1   Comparisons Work on Strings Too

Comparison operators are not just for numbers. You can compare strings with == and !=, which checks whether two pieces of text are exactly the same (including capitalisation):

username = "alex"

if username == "alex":
    print("Welcome back, Alex!")

if username != "admin":
    print("You do not have admin access.")

3   The in Operator

Python has a special operator that does something very useful: it checks whether one thing is contained inside another. This is the in operator, and it is one of Python's most readable features.

in works on two things you will use all the time:

• Strings — checking whether one piece of text appears inside another.
• Lists — checking whether a value exists anywhere in a collection. (You will learn more about lists in a later article — for now, just notice how natural the syntax feels.)

3.1   in with Strings

email = "[email protected]"

if "school.edu" in email:
    print("This looks like a school email address.")

if "@" in email:
    print("The email contains an @ symbol.")

Python reads "school.edu" in email almost like plain English: "is 'school.edu' found somewhere inside the email string?" If yes — True. If no — False.

3.2   in with Lists

allowed_users = ["alex", "sam", "priya"]
username = "sam"

if username in allowed_users:
    print("Access granted.")

Again, this reads almost like English: "if username is in the list of allowed users, grant access." This is one of the reasons Python is so readable — the code describes the logic directly.

3.3   not in — the Opposite

You can flip in to not in to check that something is absent:

banned_words = ["spam", "scam", "free money"]
message = "Click here for free money"

if "free money" in message:
    print("This message looks like spam.")

vowels = ["a", "e", "i", "o", "u"]
letter = "b"

if letter not in vowels:
    print(letter, "is a consonant.")

4   Making a Choice: if and else

A bare if statement only does something when the condition is True — it stays silent when the condition is False. Often you want to handle both cases: do one thing if true, and a different thing if false. That is what else is for.

4.1   The Structure

if condition:
    # runs when condition is True
else:
    # runs when condition is False

There are a few rules to notice:

• The condition is followed by a colon :.
• The code to run is indented (one level in — 4 spaces is standard).
• else sits at the same indentation as if, also followed by a colon.
• Only one branch runs — never both.

4.2   A Real Example

age = int(input("How old are you? "))

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

4.3   What Happens Without else?

If you only write an if with no else, the program simply moves on silently when the condition is False. This is fine when you only care about the True case:

score = 95

if score == 100:
    print("Perfect score!")

print("Thanks for playing.")    # This always runs

If score is 95, the first print is skipped and only "Thanks for playing." appears. No error, no crash — Python just moves on.

5   Handling Multiple Cases: elif

What if you have more than two possible outcomes? if/else only handles two branches — true or false. For three or more cases, Python gives you elif, which is short for "else if".

5.1   The Structure

if first_condition:
    # runs if first_condition is True
elif second_condition:
    # runs if first was False AND second_condition is True
elif third_condition:
    # runs if first and second were False AND third_condition is True
else:
    # runs if ALL conditions above were False

Key rules:

• You can have as many elif branches as you need.
• Python checks conditions top to bottom and stops at the first true one.
• The else at the end is optional — it is the "none of the above" case.
• Only one branch ever runs, no matter how many conditions are listed.

5.2   A Full Grading Example

score = int(input("Enter your score (0-100): "))

if score >= 90:
    grade = "A"
elif score >= 80:
    grade = "B"
elif score >= 70:
    grade = "C"
elif score >= 60:
    grade = "D"
else:
    grade = "F"

print("Your grade is:", grade)

5.3   A Worked Trace Table

Good programmers trace their conditionals by hand before running the code. Here is a variable state table for the grading program above with a score of 73:

6   Putting It All Together

Here is a complete program that combines everything in this article: comparison operators, the in operator, and an if/elif/else chain. Read it carefully and predict the output for a few different inputs before running it.

VIP_USERS = ["alice", "bob", "carol"]

username = input("Enter your username: ").lower()
score = int(input("Enter your score: "))

# Check access level
if username in VIP_USERS:
    print("Welcome, VIP user", username + "!")
else:
    print("Welcome,", username + ".")

# Check score and assign a rank
if score >= 90:
    rank = "Gold"
elif score >= 70:
    rank = "Silver"
elif score >= 50:
    rank = "Bronze"
else:
    rank = "Unranked"

print("Your rank is:", rank)

# Bonus message
if rank != "Unranked":
    print("Congratulations on earning a rank!")

A few things worth noticing in this program:

• .lower() converts the username to lowercase before checking — so "Alice", "ALICE", and "alice" all match. This neatly solves the case-sensitivity problem from Section 2.
• The two if blocks are independent — the access check and the rank check are separate decisions that do not interact.
• The final if uses a != comparison against the string "Unranked" to decide whether to print the bonus message.

7   Common Mistakes to Watch For

8   Final Check: The Big Picture

9   Quick-Reference: Operators at a Glance