JavaScript is a programming language launched in 1995 and is influenced by C. Often is used from browser’s built-in code, but also is used on server for development of web and mobile applications.
Includes many built in functions, also developers can create their own functionalities. Debugging is made today by console available in popular web browsers.
It can be used to work with DOM (code structure or code tree), allows to create live interactions and behaviors on the fly reacting to user actions and events.
Standard file name extension is .js and JavaScript is included and enhanced in many frameworks such as jQuery, Motools, ExtJS, NodeJS and more.