Variables and Data Types

Variables are the building blocks of every Python program. A variable is a name that refers to a value stored in your computer's memory. In this lesson, you will learn how to create variables, understand Python's core data types, and convert between them.

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Creating Variables

In Python, you create a variable simply by assigning a value to a name using the = operator:

age = 25
name = "Alice"
pi = 3.14159
is_student = True

print(age)         # 25
print(name)        # Alice
print(pi)          # 3.14159
print(is_student)  # True

There is no need to declare the type — Python figures it out automatically. This is called dynamic typing.

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Variable Naming Rules

• Must start with a letter or underscore _
• Can contain letters, numbers, and underscores
• Cannot start with a number
• Cannot use Python keywords (like if, for, class, return)
• Are case-sensitive (age and Age are different)

# Valid names
user_name = "Alice"
_count = 10
total2 = 50
MAX_SIZE = 100