Difference between implicit, explicit, default, and new binding

JavaScript resolves "this" using four main rules. Default binding applies when a function is called without a receiver object. In non-strict mode, this becomes the global object; in strict mode, this is undefined. Implicit binding applies when you call a function as a property of an object; the object to the left of the dot becomes this. Explicit binding uses call, apply, or bind to set this to a specific object regardless of how the function is invoked. New binding applies when you use new; it creates a fresh object, sets it as this inside the constructor, and returns it unless the constructor returns an object explicitly.