Python Data Types | Learn Computer Academy

Data Types

Python has several built-in data types. This lesson covers the simple ones in depth; the collection types (list, tuple, dict, set) get their own dedicated lessons shortly, since each has enough to it to deserve one.

The Simple Types

Type	Holds	Example
str	Text	"Hello"
int	Whole numbers	42
float	Decimal numbers	3.14
bool	True or False	True
NoneType	No value at all	None

Capitalization matters here

True, False, and None are capitalized in Python. Many other languages use lowercase true/false/null instead, so this trips up almost everyone coming from another language at least once.

Checking a Value's Type

x = 42
print(type(x))          # <class 'int'>
print(isinstance(x, int)) # True

The Collection Types, at a Glance

Type	Ordered?	Changeable?	Duplicates allowed?
list	Yes	Yes	Yes
tuple	Yes	No	Yes
dict	Yes (insertion order)	Yes	Keys must be unique
set	No	Yes	No

Each of these gets its own lesson soon. For now, the key thing to notice is that Python has four distinct built-in collection types, each with genuinely different rules — picking the right one for the job matters.

Python Doesn't Auto-Convert Types

Python raises an error rather than silently guessing when types don't match — this is deliberate, not a limitation:

result = "5" + 3
# TypeError: can only concatenate str (not "int") to str

The next lesson, Type Conversion, covers converting between types deliberately — which is required here, Python won't do it for you.

None, False, and 0 are not the same thing

None, False, and 0 are three different values, even though all three are falsy in an if check. None means "no value was ever set," False means "a boolean, specifically false," and 0 means "the number zero." Mixing them up — for example, using 0 as a placeholder for "not set yet" — makes bugs harder to track down later, since 0 is a perfectly valid, meaningful number in a lot of code.