What is the difference between 'null', 'undefined', and 'NaN' in JavaScript?

'null' is a value that represents the intentional absence of any object value.

'undefined' is a value that indicates the absence of a defined value, such as a variable that has not been initialized.

'NaN' stands for 'Not a Number' and is a value returned when a mathematical operation cannot be performed, such as dividing by zero or converting a string to a number that is not a valid number.

'null' and 'undefined' are primitive values, while 'NaN' is a special value of the number type.

Overall, 'null' is used to represent the absence of an object value, 'undefined' is used to represent the absence of a defined value, and 'NaN' is used to represent an error in a mathematical operation.