As you'll become very familiar with over time, developers often listen for the change or input events on forms. We do this by using JavaScript, and then perform an action based on those events happening.

But Clyde, where are these events from, and how do we access to them? 

Well, the good news is that they are given to us by the browser itself. In fact, the change and input events are from the HTMLElement interface, which is a web API given to us straight out of the box.

Anyways, I just wanted to mention this to you as you'll be seeing a lot of examples in this course where we do listen for these events and then execute code when the event fires.

Let's march on ...