Python Core | VoidX Academy

3. Python Data Types

Core Concept

Python Data Types

Every value in Python has a data type. The data type tells Python what kind of information is being stored and what operations are allowed on it. You cannot, for example, add a number to a piece of text without converting it first.

Python has a rich set of built-in data types organized into several categories. Understanding them is fundamental to writing programs that behave correctly.

The Core Built-in Types

Python's most commonly used data types are organized into these groups:

Text — str (string)
Numeric — int (integer), float (decimal), complex (complex number)
Sequence — list, tuple, range
Mapping — dict (dictionary)
Set — set, frozenset
Boolean — bool (True or False)
Binary — bytes, bytearray
None — NoneType (represents the absence of a value)

Strings (str)

A string is a sequence of characters enclosed in either single quotes or double quotes. Strings are used to represent text — names, messages, file paths, anything written.

x = "Hello, World!"
y = 'Python is awesome'

print(x)
print(y)
print(type(x))

OutputHello, World! Python is awesome <class 'str'>

You can use either single or double quotes — Python treats them identically. The key rule is to be consistent within the same string.

Integers (int)

An integer is a whole number with no decimal point. It can be positive, negative, or zero. There is no size limit to Python integers — they can grow as large as your computer's memory allows.

a = 42
b = -100
c = 0
d = 99999999999999999999  # Python handles huge numbers natively

print(a)
print(b)
print(type(a))

Output42 -100 <class 'int'>

Floats (float)

A float is a number that contains a decimal point. Floats are used whenever you need precision — prices, measurements, scientific calculations, percentages.

price = 19.99
temperature = -3.5
pi = 3.14159

print(price)
print(temperature)
print(type(pi))

Output19.99 -3.5 <class 'float'>

Floats can also be written in scientific notation using the letter e. For example, 1.5e3 means 1.5 × 10³ = 1500.0.

x = 1.5e3
y = 2.8e-2
print(x)
print(y)

Output1500.0 0.028

Booleans (bool)

A boolean represents one of only two possible values: True or False. Booleans are the foundation of all decision-making in programming — every if-statement, every while-loop, every comparison ultimately resolves to True or False.

is_logged_in = True
has_premium = False

print(is_logged_in)
print(has_premium)
print(type(is_logged_in))

OutputTrue False <class 'bool'>

In Python, True and False must be capitalized exactly. true or false in lowercase will cause a NameError.

NoneType

None is a special constant in Python that represents the absence of a value. It is not zero, not an empty string, not False — it is the deliberate absence of any value whatsoever. Functions that do not explicitly return a value automatically return None.

result = None

print(result)
print(type(result))

# Checking for None
if result is None:
    print("No value has been assigned yet.")

OutputNone <class 'NoneType'> No value has been assigned yet.

💡Best Practice: Always use is None or is not None to check for None — never use == None. The is keyword checks for identity (same object in memory), which is the correct and safe way to check for None.

3. Python Data Types

Core Concept

Python Data Types

Python has a rich set of built-in data types organized into several categories. Understanding them is fundamental to writing programs that behave correctly.

The Core Built-in Types

Python's most commonly used data types are organized into these groups:

Text — str (string)
Numeric — int (integer), float (decimal), complex (complex number)
Sequence — list, tuple, range
Mapping — dict (dictionary)
Set — set, frozenset
Boolean — bool (True or False)
Binary — bytes, bytearray
None — NoneType (represents the absence of a value)

Strings (str)

A string is a sequence of characters enclosed in either single quotes or double quotes. Strings are used to represent text — names, messages, file paths, anything written.

x = "Hello, World!"
y = 'Python is awesome'

print(x)
print(y)
print(type(x))

OutputHello, World! Python is awesome <class 'str'>

You can use either single or double quotes — Python treats them identically. The key rule is to be consistent within the same string.

Integers (int)

An integer is a whole number with no decimal point. It can be positive, negative, or zero. There is no size limit to Python integers — they can grow as large as your computer's memory allows.

a = 42
b = -100
c = 0
d = 99999999999999999999  # Python handles huge numbers natively

print(a)
print(b)
print(type(a))

Output42 -100 <class 'int'>

Floats (float)

A float is a number that contains a decimal point. Floats are used whenever you need precision — prices, measurements, scientific calculations, percentages.

price = 19.99
temperature = -3.5
pi = 3.14159

print(price)
print(temperature)
print(type(pi))

Output19.99 -3.5 <class 'float'>

Floats can also be written in scientific notation using the letter e. For example, 1.5e3 means 1.5 × 10³ = 1500.0.

x = 1.5e3
y = 2.8e-2
print(x)
print(y)

Output1500.0 0.028

Booleans (bool)

is_logged_in = True
has_premium = False

print(is_logged_in)
print(has_premium)
print(type(is_logged_in))

OutputTrue False <class 'bool'>

In Python, True and False must be capitalized exactly. true or false in lowercase will cause a NameError.

NoneType

result = None

print(result)
print(type(result))

# Checking for None
if result is None:
    print("No value has been assigned yet.")

OutputNone <class 'NoneType'> No value has been assigned yet.

3. Python Data Types

Python Data Types

The Core Built-in Types

Strings (str)

Integers (int)

Floats (float)

Booleans (bool)

NoneType

Knowledge Check

3. Python Data Types

Python Data Types

The Core Built-in Types

Strings (str)

Integers (int)

Floats (float)

Booleans (bool)

NoneType

Knowledge Check