What is Java?

Java is a very powerful and a widely used general purpose programming language.  Java was designed by James Gosling and team at Sun Microsystems back in early 1990's.  

A variety of computer processors made by different companies were used in various the household electronics like toaster, TV, etc. Each processor had its own programming instruction set. As such, for every processor, the device manufacturers had to write the same program again but differently based on the type of processor. This involved more effort to write and test the same program in an instruction set specific to the processor, thus incurring more labor, time and cost. 

The team at Sun Microsystem attempted to solve this by designing a new programming language (later to be known as Java) that would allow writing the program once irrespective of the processor thus saving time and cost for the manufacturer while allowing to use any compatible processor.

Since then the popularity of Java language has grown leaps and bound. Even though Java started as the language used for programming embedded devices, later Java became a popular choice in all most all aspects via it be building desktop applications, web applications, mobile apps, 2D-3D games etc.