Assign Variables

What is a Variable?

Think of a variable as a labeled box. You give the box a name, put a value inside it, and later you can use that name to get the value back.

In Python, you create a variable by typing: name = value

age = 25

This creates a box labeled

age

and puts the number

inside it. Now anywhere in your code, when you write

age

, Python knows you mean

The Three Main Types of Data

Python has different types of data, and it's important to understand them:

◆
Integers (int) — whole numbers:
```
25
```
,
```
100
```
,
```
-3
```
◆
Floats (float) — decimal numbers:
```
5.9
```
,
```
3.14
```
,
```
-0.5
```
◆
Strings (str) — text, always in quotes:
```
"Alice"
```
,
```
'hello'
```

name = "Alice"     # This is a string (text)
age = 25           # This is an integer (whole number)
height = 5.9       # This is a float (decimal number)

print(name)        # → Alice
print(age)         # → 25
print(height)      # → 5.9

Notice: strings need quotes, but numbers don't. If you wrote

name = Alice

without quotes, Python would think

Alice

is another variable name — and crash because it doesn't exist!

💡
💡 Naming rules: Variable names can contain letters, numbers, and underscores. They must start with a letter or underscore (not a number). Use descriptive names like
user_age
instead of
x
.