How to Create Variables in Python?

What is a Variable?

A variable is a name given to a memory location where a value is stored. You can use or change the value by writing the variable’s name.

Example:

name = "Ram"
age = 25

Here, name and age are two variables.

• name stores “Ram” (a string type).
• age stores 25 (an integer type).

How to Declare a Variable?

To create a variable in Python, simply write:

variable_name = value

Example:

city = "Delhi"
temperature = 38.5
is_raining = False

Rules for Naming Variables

Variable names must follow specific rules:

• Start with a letter or an underscore (_):
  

  2name = "Amit" (❌ Invalid)
  name2 = "Amit" (✅ Valid)

• Can contain only letters, numbers, and underscores:
  

  student_name, rollNo, marks_1 (✅ Valid)

  
  
• No spaces are allowed:
  

  student name = "Ravi" (❌ Invalid)

• Cannot be Python keywords: Keywords are reserved words like if, while, class.
• Python is case-sensitive: Name and name are considered different variables.
  

  Name = "Rahul"
  name = "Rohit"

  
  

  These are two separate variables.

Python is Dynamically Typed

You do not need to define the type of a variable. Python automatically understands the data type based on the value you assign.

x = 10       # x is an integer
x = "hello"  # Now x becomes a string

Read: Features of Python

Types of Variables

Here are some common types of data you can store in variables:

Suggested Read: Data Types in Python with Examples

Changing the Value of a Variable (Reassignment)

You can change a variable’s value after it has been created.

x = 5
x = x + 2
print(x)   # Output: 7

Multiple Variables in One Line

You can assign values to multiple variables on a single line.

Different values:

a, b, c = 1, 2, 3
print(a, b, c)  # Output: 1 2 3

Same value:

x = y = z = 100
print(x, y, z)  # Output: 100 100 100

Checking Variable Type

Use the type() function to find out a variable’s data type.

name = "Radha"
print(type(name))  # Output: <class 'str'>

marks = 90.5
print(type(marks))  # Output: <class 'float'>

Constants in Python

Python does not have a special syntax for constants. However, there’s a common convention:

• Constant variables are named in ALL CAPS.
• We assume their values will not change during program execution.

Example:

PI = 3.14159
GRAVITY = 9.8

Best Practices for Variables

Follow these guidelines for writing clear and readable code:

• Use meaningful names: Names like total_marks or user_name are clear.
• Avoid short and unclear names: x, y, a1 can make code hard to understand.
• Use snake_case: student_name and phone_number are examples of this common Python style.

Quick Practice (Guess Output)

What will this code print?

name = "Amit"
age = 30
age = age + 5
print(name, age)

Output: Amit 35

Summary

Homework for You:

Try creating these variables:

• A variable to store your best friend’s name.
• A variable for your birth year.
• A variable to check if you’re a student (True or False).
• A constant for your SCHOOL_NAME (e.g., “ABC School”).