In JavaScript, data types can be categorized into two main groups: primitive and non-primitive (also known as reference types) data types. Here's an explanation of each: 1. Primitive Data Types: These are immutable data types that store a single value. a. Boolean: Represents a logical value, either true or false. It is commonly used for conditions and branching in JavaScript. 

let isTrue = true;
let isFalse = false;
console.log(isTrue);   // Output: true
console.log(isFalse);  // Output: false
b. Number: Represents numeric values, including integers and floating-point numbers. 

let count = 10;
let price = 4.99;
console.log(count);  // Output: 10
console.log(price);  // Output: 4.99
c. String: Represents a sequence of characters enclosed in single or double quotes. Strings are used to represent textual data. 

let message = "Hello, world!";
console.log(message);  // Output: Hello, world!
d. Null: Represents the intentional absence of any object value. It is often assigned to a variable to indicate that it has no value or that the value is unknown. 

let value = null;
console.log(value);  // Output: null
e. Undefined: Represents an uninitialized or undeclared variable. If a variable is declared but not assigned a value, it will have the value of undefined. 

let variable;
console.log(variable);  // Output: undefined
f. Symbol: Represents a unique identifier. Symbols are typically used as keys in objects to avoid naming conflicts. 

let id = Symbol("unique");
console.log(id);  // Output: Symbol(unique)
2. Non-Primitive (Reference) Data Types: These are mutable data types that store references to memory locations rather than the actual values. a. Object: Represents a collection of key-value pairs and provides a way to group related data and functionality together. Objects can be created using object literals {}, constructor functions, or the class syntax introduced in ECMAScript 2015. 

let person = {
  name: "John",
  age: 30,
  isAdmin: false
};
console.log(person);  // Output: { name: 'John', age: 30, isAdmin: false }
b. Array: Represents an ordered list of values. Arrays can hold values of any type, and their elements are accessed using numeric indices starting from 0. 

let numbers = [1, 2, 3, 4, 5];
console.log(numbers);  // Output: [1, 2, 3, 4, 5]
c. Function: Represents executable code that can be invoked and performs a specific task. Functions are one of the fundamental building blocks in JavaScript and can be defined using function declarations or function expressions. 

function greet(name) {
  console.log("Hello, " + name + "!");
}

greet("Alice");  // Output: Hello, Alice!
Non-primitive data types, such as objects, arrays, and functions, are passed by reference, meaning that when you assign them to a variable or pass them as arguments to functions, you are working with a reference to the original value stored in memory. Primitive data types, on the other hand, are passed by value, meaning that when you assign them to a variable or pass them as arguments, a copy of the value is created.