Understanding Variables in Python

A variable is like a container that holds information. Think of it as a labeled box where you can store something (like numbers or text) and use it later.

What is a Variable?

In Python, a variable is used to store data. For example, if you want to remember someone’s name or age, you can save it in a variable.

How to Create a Variable

Creating a variable in Python is very simple. You just need to write a name for the variable, use the = sign, and assign it a value. Here’s the format:

variable_name = value
    

Example:

name = "John"
age = 25
    

Explanation:

• name: This variable stores the value "John" (which is text).
• age: This variable stores the value 25 (which is a number).

Using Variables

Once you create a variable, you can use it in your program. Example:

name = "John"
age = 25

print(name)
print(age)
    

Output:

John
25
    

Rules for Naming Variables

When naming variables in Python, follow these rules:

• Use only letters, numbers, or underscores (_).

# Correct:
my_name = "Python"

# Incorrect:
my-name = "Error"  # Hyphens are not allowed
      

• Do not start variable names with a number.

# Correct:
name1 = "John"

# Incorrect:
1name = "Error"  # Cannot start with a number
      

• Do not use spaces in variable names. Use underscores instead.

# Correct:
first_name = "Alice"

# Incorrect:
first name = "Error"  # Spaces are not allowed
      

• Do not use Python keywords (like print, if, or while).

# Correct:
my_variable = "Allowed"

# Incorrect:
print = "Error"  # `print` is a Python keyword
      

• Variable names are case-sensitive. That means Name and name are different variables.

# These are two different variables:
Name = "John"
name = "Doe"

print(Name)  # Output: John
print(name)  # Output: Doe
      

Types of Data You Can Store in Variables

Variables can store different types of data:

• Text (String): Use quotes for text, like "Hello" or 'Python'.
• Numbers: Whole numbers like 10 or decimal numbers like 3.14.
• True/False (Boolean): Can store either True or False.

Example:

name = "Alice"
age = 30
is_student = True
    

Why Use Variables?

Variables make your programs easier to write and read. Instead of repeating values, you can store them in variables and use them whenever needed. This makes your code clean, flexible, and easy to update.

Practice: Try It Yourself!

Write and run the following Python code:

# Storing data in variables
name = "Emma"
hobby = "painting"

# Using variables
print(name)
print(hobby)
    

Expected Output:

Emma
painting
    

Congratulations!

You’ve learned what variables are and how to use them. Keep practicing to get comfortable with storing and using data in your programs!