My explanation:
JavaScript is pretty much all the cool and pretty effects you see on most sites. JavaScript enables developers to add more customization and to create a more user friendly website. Examples of when these codes can be used: mouse over effects, drop down menus, slide shows, scrolling text, and a bunch more.

Description:
JavaScript is a scripting language used to enable programmatic access to objects within other applications. It is primarily used in the form of client-side JavaScript for the development of dynamic websites. JavaScript is a dialect of the ECMAScript standard and is characterized as a dynamic, weakly typed, prototype-based language with first-class functions. JavaScript was influenced by many languages and was designed to look like Java, but to be easier for non-programmers to work with.