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# Primitives and objects

JavaScript divides data essentially into two main categories: *primitives* and *objects*.

Let's start by defining what a primitive is:

A *primitive* is one of the simplest forms of data.

A primitive value could be thought of as an *atom*, if you're familiar with chemistry from the old days at school. An atom is the simplest form of an element, and that's exactly what a primitive is in JavaScript.

The simplest example of primitive values would be numbers. Consider the value `10`. This, as you know, is a number in JavaScript. But most importantly, it's a primitive. It's one of the simplest values that can be represented in JavaScript.

The key characteristic of primitives, as we shall discover later on, is that they don't have any properties/methods attached to them. So when we say that `10` is a primitive value, we, in effect, mean that there are no properties/methods attached to this value `10`.

JavaScript comes equipped with 7 primitive data types: `undefined`, `null`, *numbers*, *strings*, *Booleans*, *Symbols*, and *BigInt*.

For this course, we'll only be concerned with the first five. The remaining two types are covered in our [Advanced JavaScript](https://www.codeguage.com/courses/advanced-js/) course.

On the other hand, an *object* is the mirror image of a primitive.

An *object* is a value composed of primitives.

Going with the analogy that a primitive resembles an atom, an object then resembles a molecule. A molecule is made up of atoms and so are objects, which are made up of primitives.

Simply put, if a value isn't a primitive in JavaScript, then it is an object. Apart form the seven primitive data types discussed above, *everything else* is an object in the language.

An object, unlike a primitive, can have properties/methods attached to it.

An object is sometimes also referred to as a *reference*. And by that means, the object type is also known as the *reference type*. That where does the term *'reference'* come from, we'll explore later on in this chapter.

Let's now start exploring the different primitive types in JavaScript before considering its object types.