Intrinsic function are built-in functions by Javascript, sort of like how the notification center is built in to a phone. Examples of intrinsic functions in JavaScript include: Math.sin() Math.random() Array.prototype.forEach() String.prototype.substring() Object.keys() These functions are are optimized by JavaScript engine and generally are faster and more efficient than custom functions. They also provide a standardized way of performing common tasks, making your code more predictable and easier to maintain