Basic Types: int, float, str, bool, None

Python has five fundamental built-in types that you'll use constantly. Understanding how they work — and how they differ from each other — is essential for writing correct Python code.

Integers (int)

Integers are whole numbers with no decimal point. Python's integers have arbitrary precision — they can be as large as your memory allows, unlike C or Java where integers overflow.

Note that / always returns a float in Python 3, even if the result is a whole number:

You can write integer literals with underscores for readability:

Floating-Point Numbers (float)

Floats represent real numbers with a decimal point. Python uses IEEE 754 double-precision floating-point (64-bit).

The Floating-Point Precision Trap

Floats cannot represent all decimal values exactly because they're stored in binary:

This is not a Python bug — it's how IEEE 754 works in all languages. To compare floats safely:

Special float values:

Strings (str)

Strings are sequences of Unicode characters. Python has no separate char type — a single character is just a string of length 1.

String immutability — you cannot change a string in place:

Booleans (bool)

Booleans represent truth values. In Python, bool is actually a subclass of int:

Truthiness and Falsiness

Every Python value has a boolean interpretation. These values are falsy (evaluate to False):

None

None is Python's null value — it represents the absence of a value. It's the single instance of the NoneType class.

The type() Function

type() returns the type of any value:

isinstance() — Type Checking

isinstance() is the preferred way to check types because it handles inheritance:

Type Coercion / Conversion

You can convert between types using built-in functions:

Summary Table

All basic types are immutable — operations on them always create new objects rather than modifying in place.