JavaScript is part of the trinity that forms the basis for web design. HTML and CSS are the other two. JavaScript makes it interactive. Where you can press buttons, click on things, write in text boxes and answer questions. It does something in other words rather than jsut sitting there to be read.

JavaScript can be used for more than typing in an email address. It is growing in its use for a wide range of purposes. You can control robots over the internet remotely and other aspects of physical computing. It is also used in games like Unity3D. It is a very power coding language to use and as a result it looks more challenging than HTML or CSS or even C++ but the benefits are immense.