In this exercise, it says that ES6 is backwards compatible with ES5. What does it mean when something is backwards compatible?
When something, usually a device or technology, is backwards compatible, it is able to support features of the previous version, such as software or hardware. For example, the Wii gaming console was backwards compatible with the GameCube, its predecessor, as it could play GameCube games and also use the GameCube controllers.
ES6 is backwards compatible with ES5 which means that it is able to support all of the ES5 code.