Variables & Data Types

Store and work with different kinds of data

Variables — Storing Data in Python

What Is a Variable?

A variable is a named container that holds a value in your computer's memory. Think of it like a labeled box: the label is the variable name, and whatever you put inside is the value.

When you write name = "Alice", Python carves out a spot in memory, labels it name, and stores "Alice" inside. Later, whenever you use name in your code, Python retrieves whatever's in that box.

� **Analogy:** Variables are like contact names in your phone. Instead of dialing a number every time, you save it as "Mom" or "John" and use the name instead.

Syntax

python

name = "Alice"
age = 25
print(name, age)

Part	What it's called	What it does
`name`	Variable name	You choose this — make it descriptive!
`=`	Assignment operator	Takes the value on the right and stores it in the name on the left
`"Alice"`	String value	Text data (must be in quotes)
`25`	Integer value	Whole number (no quotes needed)

How It Works

When Python runs the code above:

**Line 1**: Python creates a box labeled `name` and puts `"Alice"` inside it

**Line 2**: Python creates another box labeled `age` and puts `25` inside it

**Line 3**: `print()` looks up both boxes, retrieves their values, and displays them

The output is:

Alice 25

Why Use Variables?

Without variables, every value in your code would be hard-coded — fixed and unchangeable. That works for a one-line script, but fails for any real program.

Real-world examples:

A **game** stores your health, score, and player name in variables

A **bank app** stores your account balance, transaction history, and user ID

A **weather app** stores the current temperature, forecast, and location

**Config settings** like `theme = "dark"` or `volume = 0.8`

Variables let your code adapt — ask the user for their name, store it in a variable, and use it throughout the program.

Data Types

Python automatically knows what *kind* of data a variable holds:

Type	Name	Examples
`int`	Whole numbers	`42`, `-5`, `0`, `1000`
`float`	Decimal numbers	`3.14`, `-0.5`, `2.0`
`str`	Text (strings)	`"hello"`, `"Python"`, `"42"`
`bool`	True/False	`True`, `False`

Common Mistakes

❌ Wrong	Why	✅ Right
`name = Alice` (no quotes)	Python looks for a variable called `Alice` — NameError!	`name = "Alice"`
`my name = "Alice"` (space)	Python sees 3 separate tokens — syntax error	`my_name = "Alice"`
`age = "25"` (quotes on number)	It's a string now — you can't do math with it	`age = 25`
`Name = "Alice"` then `print(name)`	Python is case-sensitive — `Name` and `name` are different!	Be consistent with lowercase

Your Turn!

Create a variable called favoriteColor and set it to your favorite color (as a string). Then create a variable called year and set it to the current year (as a number). Print both variables.

💡Need a hint? (3 available)

#1Use = to assign a value

#2Strings go in quotes, numbers do not

#3Use commas to print multiple things: print(var1, var2)

🔑Show solution (try it yourself first!)

favoriteColor = "Blue"
year = 2026
print(favoriteColor, year)

✏️ Code Editor

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📤 Output

Write your solution and click "Run Code" to test it!

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