Java was developed by
Sun in 1995 in the hope of creating a portable language, that could run on all platforms including internet browsers.
In the past programs developed on the PC had to be edited to work on the Mac and viserverser.
Java is written in plain text, much like C/C++ and then complied into byte codes very simular to machine code but not machine specific.
This code (CLASS file) is then run by a Java interpreter on the client machine, you can get one for most systems including Apple Macs, Linux and PCs.
Java interpreter or Java Virtual Machine (JVM) acts as an emulator to run the CLASS file and in turn execute on the target machine.

Java Applet
Java Applets are simply java programs that are run by a special client (i.e. a web browser).
The main differences between this and a normal Java Application are the restrictions placed on it.
The Security of Applets is very high, they can not (can be enabled in some browsers) view/read or write to your hard drive,
This is by design as you may not have a hard drive or you may not want anyone tampering with it, also they can not connect to other internet domains (again some browsers allow this).
If the applet was allowed to connect to any domain any inoccent user could active an applet on a web page and it would send nasty messages to any server on the network/internet, or at least send blocking data stopping normal data getting to the server.
The Applet must be prepared for any envetuality that can happen in the browser like the page changing or being resized.
Most internet browsers will support Java, either directly or via a plugin see your browsers documentaion for more information.

JavaScript was developed by Netscape and Sun in 1995/6 to enhanse static web pages and looks a lot like C/C++ and Java.
It is not complied, but is interpreted on the client (some server javascript is possible but this is transparent to the user).
JavaScript is quite different to Java and should not be confused as such (but commonly is).

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Page last updated 18/10/2001