ava started as a project called "Oak" (The name came from an oak tree that stood outside the Sun Microsystems office) by James Gosling in June 1991 for use in a set top box project.^[3] Gosling's goals were to implement a virtual machine and a language that had a familiar C/C++ style of notation. The first public implementation was Java 1.0 in 1995. It promised "Write Once, Run Anywhere" (WORA), providing no-cost runtimes on popular platforms. It was fairly secure and its security was configurable, allowing network and file access to be restricted. Major web browsers soon incorporated the ability to run secure Java "applets" within web pages. Java became popular quickly. With the advent of "Java 2", new versions had multiple configurations built for different types of platforms. For example, J2EE was for enterprise applications and the greatly stripped down version J2ME was for mobile applications. J2SE was the designation for the Standard Edition. In 2006, new "J2" versions were renamed Java EE, Java ME, and Java SE, respectively.

In 1997, Sun approached the ISO/IEC JTC1 standards body and later the Ecma International to formalize Java, but it soon withdrew from the process.^[4][5][6] Java remains a proprietary de facto standard that is controlled through the Java Community Process.^[7] Sun makes most of its Java implementations available without charge, with revenue being generated by specialized products such as the Java Enterprise System. Sun distinguishes between its Software Development Kit (SDK) and Runtime Environment (JRE) which is a subset of the SDK, the primary distinction being that in the JRE the compiler is not present.

On November 13, 2006, Sun released parts of Java as free/open source software, under the GNU General Public License (GPL). The release of the complete source code under GPL is expected in the first half of 2007.