When Sun Microsystems first unveiled Java in 1995, it was hard to define. That’s because Java has several parts: It is, of course, an object-oriented programming language. Java is also a standard (or multiple standards, including mobile, standard, and enterprise versions) that defines the language, as well as the libraries that a programmer can expect to have available with each version. Finally, Java is a “virtual machine” (the “JVM”), a software environment on which Java programs execute. You can only run Java programs if you have a JVM — but JVMs are available for every platform you can imagine, making Java a highly portable language.