Python in Keyword

Last Updated : 17 Jul, 2026

The in keyword is a membership operator used to check whether an element exists in a sequence, such as a list, tuple, string, set, or dictionary. It returns True if the element is found; otherwise, it returns False.

Python 
text = "Python Programming"

if "Python" in text:
    print("Found")
else:
    print("Not found")

Output
Found

Explanation: condition "Python" in text checks whether the substring "Python" is present in the string text. Since it exists, the condition evaluates to True, and the print() statement is executed.

Syntax

The general syntax of the in keyword is shown below:

element in sequence

Or, it can be used inside an if statement as follows:

if element in sequence:
# code

Explanation: in keyword checks whether an element exists in a sequence. It returns True if the element is found; otherwise, it returns False.

In Conditional Statements

The in keyword is used with if statements to check whether an element exists in a sequence.

Python 
fruits = ["apple", "banana", "mango"]

if "banana" in fruits:
    print("Banana is available")

Output
Banana is available

Explanation: in keyword checks whether "banana" exists in the list. Since it is present, the condition evaluates to True.

In for Loops

The in keyword is also used in for loops to iterate over the elements of a sequence.

Python 
colors = ["Red", "Green", "Blue"]

for color in colors:
    print(color)

Output
Red
Green
Blue

Explanation: for loop uses the in keyword to access each element of the list one by one.

With Dictionaries

When used with dictionaries, the in keyword checks whether a key exists in the dictionary.

Python 
student = { "name": "Yoir", "marks": 90 }
if "marks" in student:
    print(student["marks"])

Output
90

Explanation: in keyword checks whether "marks" is a key in the dictionary. Since the key exists, its corresponding value is printed.

With Strings

The in keyword can be used to check whether a character or substring exists in a string.

Python 
message = "Welcome to Python"

print("Python" in message)
print("Java" in message)

Output
True
False

Explanation:

  • "Python" is present in the string, so the result is True.
  • "Java" is not present, so the result is False.

With Sets

The in keyword provides a simple way to check whether an element exists in a set.

Python 
vowels = {"a", "e", "i", "o", "u"}
if "e" in vowels:
    print("e is a vowel")

Output
e is a vowel

Explanation: in keyword checks whether "e" is present in the set. Since it exists, the condition evaluates to True.

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