Java is a computer programming language, developed by Sun Microsystems in 1995, that can be used on any type of computing device. As long as the recipient has Java installed, a document or application created in this language can be opened on a Mac, a PC or other operating system. And it's likely that the recipient will have Java installed as it's one of the most popular computer programs in the world, much liked by web developers and designers. This is good as the complications involved in opening documents that have been created using software different from your own can be very frustrating.