Lesson 2: Variables & Basic Data Types

1. What are Variables?

A variable is a named container that stores a value — like a box with a label.

Examples:

age = 25
name = "Alex"
height = 1.78
is_student = True

Rules: letters, numbers, underscore; cannot start with number; case-sensitive.

2. Basic Data Types

• int: whole numbers (age = 25)
• float: decimal numbers (height = 1.78)
• str: text/strings ("Hello" or 'World')
• bool: True or False

Use type() to check:

print(type(42))      # 
print(type(3.14))    # 
print(type("AI"))    # 
print(type(True))    # 

Summary – Lesson 2

• Variables store data with names
• Main types: int, float, str, bool
• Use = to assign, type() to check

Next: operators (math & comparisons).