Programming Fundamentals › Programming Basics
Primitive Type
A built-in basic type such as integer, float, boolean or character.
Also known as: primitive data type, primitives, built-in type, scalar type
A primitive type is one of the basic, built-in types that a language provides, from which everything else is built. They hold a single simple value, as opposed to a collection or an object.
| Primitive | Examples |
|---|---|
| Integer | 42 (integers) |
| Floating point | 3.14 (floating point) |
| Boolean | true (boolean) |
| Character / string | "a", "hello" (strings) |
| Null / none | null, None (null) |
Which types count as primitive depends on the language. JavaScript’s are string, number, bigint, boolean, undefined, null and symbol. Java has int, double, boolean, char and a few more, with strings as objects. In Python, everything is technically an object, but people still call numbers, strings and booleans the basic types.
What primitives have in common
- They’re compared by value.
5 === 5is true. Objects are compared by identity (equality vs identity). - They’re immutable in most languages. You can’t change the number 5, only replace a variable’s value (mutable vs immutable).
- Copying one copies the value, so changing the copy doesn’t change the original.
let a = 5;
let b = a;
b = 10; // a is still 5Why it matters
Primitives behave differently from objects and arrays when you pass them around or compare them. Knowing which you have explains many surprises (pass by value vs reference).