Good explanation, with one nitpick: the diff is done between the _old_ virtual DOM tree and the _new_ virtual DOM tree, not between the virtual DOM tree and the real DOM. That's why you can have a component that renders a single div, and then get the reference to the real DOM node and use jQuery or some other DOM-manipulating library to attach non-React-based DOM elements to the div. As far as React knows, you're just telling it to keep rendering that same div, so nothing needs to change.