What it is: Java is a class-based, object-oriented programming language developed by Sun Microsystems in the 1990s. It’s one of the most in-demand programming languages (used by some 9 million developers and running on 7 billion devices worldwide.), a standard for enterprise software, web-based content, games and mobile apps, as well as the Android operating system. Java is designed to work across multiple software platforms, meaning a program written on Mac OS X, for example, could also run on Windows. It’s not going anywhere anytime soon and is used to power company websites like LinkedIn.com, Netflix.com and Amazon.com.