Java has been around since 1991, developed by a small team of Sun Microsystems developers in a project originally called the Green project. The intent of the project was to develop a platform-independent software technology that would be used in the consumer electronics industry. The language that the team created was originally called Oak.
The first implementation of Oak was in a PDA-type device called Star Seven (*7) that consisted of the Oak language, an operating system called GreenOS, a user interface, and hardware. The name *7 was derived from the telephone sequence that was used in the team's office and that was dialed in order to answer any ringing telephone from any other phone in the office. This PDA-type device was intended to be sold to consumer electronics manufacturers who would distribute the boxes under their company name. In 1993, the team, then incorporated as FirstPerson, Inc., decided to gear their technology toward a new implementation for which demand was building in the entertainment industry-interactive television. They proposed their technology to Time Warner as an operating system for set-top boxes and video-on-demand technology that would decode the data stream that Time Warner would be sending to television sets around the country. In June of 1993, Time Warner selected Silicon Graphics' technology over Sun's. A later deal fell apart and FirstPerson decided to disband. Half of the members of the original FirstPerson team continued to work with the Oak technology, however, applying it to multimedia and network computing.
Around the time the FirstPerson project was floundering in consumer electronics, a new craze was gaining momentum in America; the craze was called "Web surfing." The World Wide Web, a name applied to the Internet's millions of linked HTML documents was suddenly becoming popular for use by the masses. The reason for this was the introduction of a graphical Web browser called Mosaic, developed by ncSA. The browser simplified Web browsing by combining text and graphics into a single interface to eliminate the need for users to learn many confusing UNIX and DOS commands. Navigating around the Web was much easier using Mosaic.
It has only been since 1994 that Oak technology has been applied to the Web. In 1994, two Sun developers created the first version of HotJava, then called WebRunner, which is a graphical browser for the Web that exists today. The browser was coded entirely in the Oak language, by this time called Java. Soon after, the Java compiler was rewritten in the Java language from its original C code, thus proving that Java could be used effectively as an application language. Sun introduced Java in May 1995 at the SunWorld 95 convention.
Web surfing has become an enormously popular practice among millions of computer users. Until Java, however, the content of information on the Internet has been a bland series of HTML documents. Web users are hungry for applications that are interactive, that users can execute no matter what hardware or software platform they are using, and that travel across heterogeneous networks and do not spread viruses to their computers. Java can create such applications.
On the Internet, Java programs are called applets. Applets are Java applications that are embedded inside HTML files and can be downloaded into a Java-capable browser with the click of a mouse. Applets are different from regular Java applications. A Java application simply has a single main() method that indicates to the Java runtime system that it is an application. A Java applet is an application that includes several additional methods that the runtime system uses that tell it how to handle the applet, such as what to do when a user clicks an applet icon and how it looks on a page.
Before your browser's runtime Java interpreter downloads and executes the applet's code, the Java interpreter verifies the code's integrity. Java is more than a tool to help you write applets, however. It is a new, powerful programming environment.