JavaFX toolkit is the stuff hidden under the hood of the JavaFX. It's a set of native and Java libraries that handles all the complexity of the drawing UI objects, managing events, and working with various hardware. Luckily, they are well-shielded by the API from the user. We will have a brief overview of the major components. It can be useful, for example, during debugging your application; by knowing these component names, you will be able to identify potential problems from stack traces or error messages.