What is 'Java'

Java is a programming language developed by Sun Microsystems. It is designed to have the ability to run across multiple operating systems and on various manufacturers’ architectures. The phrase “Write Once Run Anywhere” conveys the idea that once compiled, it can run on a variety of platforms and chipsets. Java technology is present in everything from computers and gaming systems to smartphones and televisions.


Java was developed by a team at Sun Microsystems led by James Gosling while trying to implement a virtual machine and a language that was simpler and more uniform what was available at the time for embedded devices. After toying with various concepts, Java emerged as a cross-platform and cross-architecture platform. Sun unveiled Java in 1995, with the release of the Netscape browser.

A Java Overview

Java programs consist of instructions and parameters written as byte code. Java Virtual Machine (JVM) is a set of programs that allows the execution of instructions written in Java byte code and is the key component for providing Java its cross-platform functionality. JVM acts as an emulator that allows Java programs to run in sandbox-like isolation from the rest of the operating system to avoid potential conflicts. It also acts as an interpreter or translator that converts byte code into machine code so that any operating system running JVM can run Java programs and applets.

Java Runtime Environment (JRE) is required for running Java programs, and consists of JVM, as well as program core classes, supporting libraries, and deployment technologies. JRE is available as a standalone installation, as part of a Java Development Kit, or in Java installation packages such as Java Standard Edition (Java SE) and Java Enterprise Edition (Java EE), to name a few. Java Development Kits, in addition to containing JRE, contain the compilers, debuggers and tools needed to write and test Java applets and programs.

A Java Plug-in is a deployment technology that provides a connection between a browser and the Java platform to allow the browser to download applets. Applets are bits of programming code that were once popular methods for enhancing the functionality of web pages by providing interactive features in a web browser. Other technologies such as Flash and HTML5 have largely supplanted applets in providing this functionality.

Java is often confused with JavaScript, an unrelated programming language that, aside from a few syntax and naming similarities, has no connection to the Java language or the Java platform developed by Sun. JavaScript was a creation of Netscape and Mozilla.

Oracle bought Sun and Java in 2009 and released Java as open source under a general public use license. As of 2015, Java is still present in devices such as mobile handheld devices and supercomputers used in scientific laboratories. Java technology powers programs such as Google Earth, online games and the Android mobile operating system. Although some Java features are no longer relevant, the Java platform continues to be an important and pervasive technology.