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"Java : An object-oriented programming language developed by Sun Microsystems. A 'write once, run anywhere' programming language."

-Sun Microsystems

J ava is a programming language that was introduced in 1995 by Sun Microsystems. Because of its portability (the ability of the same code to execute on many different machines) it is wildly popular in the internet community -- a place where a large number of users with many different types of machines are accessing the same data.

Interpreted Languages
Java is an interpreted language. When java code is compiled a set of instructions (byte-codes) are generated for a virtual machine (the JVM - Java Virtual Machine). This is in contrast to the function that most compilers serve, which is to generate a set of machine specific executable instructions. Because the java language is compiled for a

virtual machine and the byte-codes generated are platform independent it is possible for the code to be run on any computer platform. The operating systems convert this virtual machine byte-code into usable instructions through a Java Interpreter. This interpretation and conversion process is one of the many functions that newer web browsers can perform.

Security
Java was designed with security in mind. Browsers provide a significant level of security protection for you. This type of security, often called the "sandbox model", involves the placing of code into a "sandbox" where it can play safely without harming or doing any real-world damage. An applet, running in the sandbox, can not write files to the disk or read files from the disk. This prevents an applet

from taking anything off of your computer and it prevents an applet from leaving anything behind. If an applet tries to do anything outside of what is permitted within the sandbox rules, the security manager throws and exception and prevents the operation from executing.

Platform Independent Software
Software developed in java is compiled into a format that is platform independent. Most operating systems currently provide for interpretation of java code. Software developed in java (such as the software which can be used on this site) can be run safely on your computer -- regardless of what kind of computer that is. This allows the programmer to write, debug, and deliver a piece of code that is capable of running safely on all of the various operating systems.