Python Variables and Data Types

Learn Python variables and data types in simple words. This beginner-friendly tutorial covers strings, integers, booleans, lists, dictionaries, and more with examples.

If you’re just starting your Python journey, one of the first and most important things you need to understand is variables and data types. Think of them as the foundation of every Python program you’ll ever write.

In this post, we’ll break it down in simple words. You’ll learn:

• What variables are
• How to create them
• What different data types exist
• Real-world examples

Let’s dive in!

What is a Variable?

A variable is like a container that stores information. In Python, you can store data like numbers, text, or even a list of items inside a variable and use it later.

Simple Example:

name = "Tejas"
age = 25

name = "Tejas"
age = 25

• name is a variable storing a text value ("Tejas")
• age is a variable storing a number (25)

You can think of it like labeling boxes:

Box labeled ‘name’ contains: Tejas

Box labeled ‘age’ contains: 25

Rules for Naming Variables in Python

Before you start using variables, keep these simple rules in mind:

✅ Can contain letters, numbers, and underscores
✅ Must start with a letter or underscore
✅ Case-sensitive (Name and name are different)
❌ Cannot start with a number
❌ Cannot use spaces or special characters

Valid examples:

first_name = "Amit"
_total = 100
marks2 = 75

first_name = "Amit"
_total = 100
marks2 = 75

Invalid examples:

2marks = 75     # ❌ starts with a number
my-name = "Amit" # ❌ contains a hyphen

2marks = 75     # ❌ starts with a number
my-name = "Amit" # ❌ contains a hyphen

Common Data Types in Python

Python is dynamically typed, which means you don’t need to tell Python what type of data you are storing — it figures it out for you!

Let’s look at the most common data types:

String (str) – Text

greeting = "Hello"

greeting = "Hello"

Strings are always enclosed in quotes (' ' or " ").

Integer (int) – Whole numbers

roll_number = 101

roll_number = 101

Float (float) – Decimal numbers

percentage = 85.6

percentage = 85.6

Boolean (bool) – True or False

is_passed = True

is_passed = True

List (list) – Collection of items

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

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

Lists are enclosed in square brackets and can store multiple values.

Tuple (tuple) – Immutable list

dimensions = (10, 20)

dimensions = (10, 20)

Tuples are like lists, but you can’t change their values after creation.

Dictionary (dict) – Key-Value pairs

student = {"name": "Anjali", "age": 22}

student = {"name": "Anjali", "age": 22}

Used for structured data. Think of it like a mini-database.

Read More: Introduction to Python

Checking Data Type with type()

Want to check what type of data a variable is holding? Use the built-in type() function.

x = 42
print(type(x))  # Output: <class 'int'>

x = 42
print(type(x))  # Output: <class 'int'>

Try it with different data types:

print(type("SmartTejas"))
print(type(3.14))
print(type(True))

print(type("SmartTejas"))
print(type(3.14))
print(type(True))

Type Conversion in Python

Sometimes, you may want to change a variable from one data type to another. This is called type casting.

Example:

x = "100"
y = int(x)   # Converts string to integer
print(y + 50)  # Output: 150

x = "100"
y = int(x)   # Converts string to integer
print(y + 50)  # Output: 150

Common conversions:

• int() → to integer
• float() → to float
• str() → to string
• bool() → to boolean

Real-Life Example: Student Report

name = "Ritu"
math = 90
science = 85
average = (math + science) / 2
passed = True

print("Student Name:", name)
print("Average Marks:", average)
print("Passed:", passed)

name = "Ritu"
math = 90
science = 85
average = (math + science) / 2
passed = True

print("Student Name:", name)
print("Average Marks:", average)
print("Passed:", passed)

FAQs – Python Variables and Data Types

Summary

Here’s what you learned today:

Mastering variables and data types is the first big step in Python programming. Practice creating your own variables and experimenting with different types.

What’s Next?

In the next post, we’ll learn about the Input and Output in Python