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Data Types (str, int, float, bool)

Python has several built-in data types. The four most common are: str (text), int (whole numbers), float (decimal numbers), and bool (True/False). Understanding types is essential for writing correct programs.

20 min•By Priygop Team•Updated 2026

Python Data Types

str - Text: 'Hello', "World", '''multiline'''
int - Whole numbers: 42, -10, 0, 1_000_000
float - Decimal numbers: 3.14, -0.5, 1.0
bool - True or False (capital T and F)
NoneType - None (represents 'no value')
type() - Check the type of any variable
Python is dynamically typed - variables can change type

Data Types Code

# String
name = "Alice"
greeting = 'Hello'
multiline = """This is
a multiline string"""

# Integer
age = 25
negative = -10
big_number = 1_000_000  # underscores for readability

# Float
price = 9.99
pi = 3.14159

# Boolean
is_active = True
is_deleted = False

# NoneType
result = None

# Check types with type()
print(type(name))       # <class 'str'>
print(type(age))        # <class 'int'>
print(type(price))      # <class 'float'>
print(type(is_active))  # <class 'bool'>
print(type(result))     # <class 'NoneType'>

# f-strings for formatted output
print(f"{name} is {age} years old")

Tip

Use type() to check any variable's type during debugging. Also use isinstance(value, int) for type checking in production code - it's more robust and handles inheritance.

Diagram

Loading diagram…

Everything in Python is an object - use type() to check

Common Mistake

Warning

Floating point math is imprecise: 0.1 + 0.2 == 0.30000000000000004, not 0.3. For financial calculations, use the decimal module: from decimal import Decimal.

Practice Task

Note

Explore data types: (1) Create one variable of each type (str, int, float, bool, None). (2) Use type() on each. (3) Try 0.1 + 0.2 and observe the result. (4) Test bool() on 0, '', [], None.

Quick Quiz

Key Takeaways

Python has several built-in data types.
str - Text: 'Hello', "World", '''multiline'''
int - Whole numbers: 42, -10, 0, 1_000_000
float - Decimal numbers: 3.14, -0.5, 1.0

Topics in This Module

Data Types Code

# String
name = "Alice"
greeting = 'Hello'
multiline = """This is
a multiline string"""

# Integer
age = 25
negative = -10
big_number = 1_000_000  # underscores for readability

# Float
price = 9.99
pi = 3.14159

# Boolean
is_active = True
is_deleted = False

# NoneType
result = None

# Check types with type()
print(type(name))       # <class 'str'>
print(type(age))        # <class 'int'>
print(type(price))      # <class 'float'>
print(type(is_active))  # <class 'bool'>
print(type(result))     # <class 'NoneType'>

# f-strings for formatted output
print(f"{name} is {age} years old")

Topics in This Module