Variables in Python

Every serious program stores information. Usernames, prices, counters, scores, settings — everything is stored using variables.

A variable is a named reference to a value stored in memory. It allows us to save data and reuse it throughout a program.

Creating Variables

In Python, you create a variable by assigning a value using the equal sign.

# Assigning values to variables

x = 10                # integer
name = "Dataplexa"    # string
price = 499.99        # float

Explanation

• x stores a whole number.
• name stores text inside quotes.
• price stores a decimal number.
• The = operator assigns the value to the variable.
• Python automatically decides the data type.

Displaying Variable Values

Variables remain in memory unless we display them. To see the stored value, we use the print() function.

x = 10
name = "Dataplexa"

print(x)        # print number
print(name)     # print string

• print() sends output to the screen.
• Without print(), values stay inside memory only.

Reassigning Variables

Variables can change over time. Python always keeps the most recent value.

x = 10          # initial value
x = 20          # updated value

print(x)

• The original value (10) is replaced by 20.
• Memory now stores only the latest value.

Dynamic Typing

Python is dynamically typed. You do not declare variable types explicitly.

value = 100          # integer
value = "Hello"      # now string
value = 3.14         # now float

print(type(value))

• The variable type changes when the value changes.
• Python automatically detects the type.

Multiple Assignment

Python allows assigning multiple variables in one line.

# Assign three values at once
a, b, c = 10, 20, 30

print(a, b, c)

• Values are assigned from left to right.
• This keeps code clean and efficient.

Swapping Variables

Python provides a clean way to swap values without using a third variable.

x = 5
y = 10

# Swap values
x, y = y, x

print(x, y)

• No temporary variable required.
• This is a common Python feature.

Real-World Example: Simple Billing System

Let us simulate a small billing calculation to see variables working together.

# Product information
item_price = 799      # price of one item
quantity = 2          # number of items purchased
tax_rate = 0.18       # 18% tax

# Calculations
subtotal = item_price * quantity
tax = subtotal * tax_rate
total = subtotal + tax

# Output results
print("Subtotal:", subtotal)
print("Tax:", tax)
print("Total:", total)

How This Works

• item_price stores the price.
• quantity stores the count.
• subtotal multiplies price and quantity.
• tax calculates tax amount.
• total combines subtotal and tax.
• Each variable builds on previous values.

Types of Variables in Python

In the next lesson, we will explore these data types in detail.

Practice

Quick Quiz

Recap: You learned how variables store data, how assignment works, how values update, and how variables support real-world calculations.

Next up: Understanding Python Data Types in depth.