Introduction

Java refers to a number of computer software products and specifications from Sun Microsystems (the Java™ technology) that together provide a system for developing and deploying cross-platform applications. Java is used in a wide variety of computing platforms spanning from embedded devices and cell phones on the low end to enterprise servers and super computers on the high end. Java is fairly ubiquitous in cell phones, Web servers and enterprise applications, and somewhat less common in desktop applications, though users may have come across Java applets when browsing the Web.

For years, Sun Microsystems referred to Java as the "Java technology" but has used the word "Java" as an adjective about the technology. In practice, many programmers have used the word "Java" to mean the programming language, while the execution platform was called the "JRE" (Java Runtime Environment) and the compiler-system was called the "JDK" (Java Development Kit), rather than a "Java compiler" as such. The word "Java" has often been used as an adjective, but the formal term "Java technology" should be noted (see history below).