Variables & Data Types

Understanding variables and data types is the first step to becoming a programmer.
These two concepts help computers store, organize, and process information.

Think of them as:

*Variables → containers to store data
*Data Types → what kind of data stored in that container

What is a Variable?

• A variable is a named storage location in memory that holds a value.
  
  
• You can change it, update it, or use it in calculations.

* In real life:

         Imagine a box with a label.

Label = variable name

Content inside = variable value

Example:

age = 18

Why Do We Need Variables?

• To store user input
  
  
• To perform calculations
  
  
• To store data from sensors
  
  
• To track score in games
  
  
• To hold login information
  
  
• To save results
  
  
• Without variables,
  
  

Computers would have no memory --- just one-time actions.

How to Declare Variables (Examples)

Python

name = "Declare"

score = 95

C

int age = 20;

float height = 5.8;

JavaScript

let city = "Chennai";

const pi = 3.14;

Different languages, different styles --- but same idea.

What Are Data Types?

A data type decides what kind of value a variable can store.

Examples:

Numbers: 18, 3.14

Text: "Hello"

True/False: True

Collection: [1, 2, 3]

Different types of data need different storage and operations.

Basic Data Types  Explained Simple

 Integer (Whole Numbers)

Used for whole numbers:

0, 1, 10, 500, -20

Examples:

age = 18

score = -5

Computers store integers efficiently  no decimals.

Float / Double (Decimal Numbers)

Any number with a decimal:

3.14

99.99

0.5

Examples:

height = 5.7

price = 99.99

Used in:

Banking

Physics

Games

Measurements

AI calculations

String (Text Data)

Represents text — characters inside quotes.

name = "Yuva"

city = "Chennai"

Everything you type inside " "

or ' ' becomes a string.

Even numbers:

"123" → string

123   → number

Boolean (True / False)

Only two values:

• True
  
  
• False

Used for decisions:

is_logged_in = True

has_money = False

• This is the core of:
  
  
• IF conditions
  
  
• Login systems
• 
  
• Game mechanics
  
  
• Sensors (on/off)

Composite / Advanced Data Types (Intro Level)

These store multiple values at once.

List / Array

• Ordered collection
  
  
• [10, 20, 30]
  
  
• Dictionary / Object
  
  
• Key → value pair
  
  
• {"name": "Yuva", "age": 18}

Tuple

Fixed group of values

(4, 6, 8)

These are powerful and used in real projects.