In JavaScript, `null` and `undefined` are two distinct primitive values that represent the absence of a meaningful value. Although they are similar in some ways, they have subtle differences. Here's a breakdown of the differences between `null` and `undefined`: 1. Assignment: `undefined` is a default value assigned to a variable that has been declared but has not been assigned a value. On the other hand, `null` is a value that can be assigned explicitly to a variable by the programmer to indicate the absence of an object or an empty value. 2. Type: `undefined` is a type itself in JavaScript and represents the absence of a value. It is considered a primitive value. On the other hand, `null` is an object type, which means it is an empty object reference. 3. Usage: `undefined` is commonly used to indicate the absence of a value, such as when a variable has not been assigned a value or when a function does not return a value explicitly. `null`, on the other hand, is typically used to indicate the intentional absence of an object or value. 4. Behavior: When you try to access a variable that has been declared but not assigned a value, it will have the value of `undefined`. When a function does not return a value explicitly, it implicitly returns `undefined`. On the other hand, `null` must be assigned explicitly by the programmer and is not assigned automatically. 5. Strict Equality: In JavaScript, `undefined` and `null` are not strictly equal to each other (`undefined === null` evaluates to `false`). They are distinct values with different types. 6. Type Coercion: When performing loose equality comparisons (using `==`), `null` and `undefined` are loosely equal to each other (`null == undefined` evaluates to `true`). However, when using strict equality comparisons (using `===`), they are not equal (`null === undefined` evaluates to `false`). 7. Passing Arguments: If a function parameter is not supplied with an argument, its value will be `undefined`. However, if you explicitly pass `null` as an argument, it will be assigned to that parameter. In summary, `undefined` represents the absence of a value or an uninitialized variable, while `null` represents the intentional absence of an object or an empty value. They have different types, behaviors, and use cases in JavaScript.