# JavaTM 2 SDK and Java Runtime Environment

## Overview

There are two principal products in the JavaTM 2 Platform, Standard Edition, (J2SETM) platform family.

Java Runtime Environment (RE)
  The Java RE provides the libraries, Java virtual machine, and other components necessary for you to run applets and applications written in the Java programming language. It does not contain tools and utilities such as compilers or debuggers for developing applets and applications.

Java 2 Software Development Kit (SDK)
  The Java 2 SDK is a superset of the Java RE. The Java 2 SDK contains everything that's in the Java RE, plus additional tools such as compilers and debuggers that are necessary for developing applets and applications.

Question: Why would anyone want the Java RE if the Java 2 SDK has everything in the Java RE and more?

Answer: The Java RE is smaller and therefore easier to download or distribute with software than the Java 2 SDK. Most users of Java technology are people who just want to run applets and applications developed by others. They're not interested in developing any applications themselves. The relatively small Java RE is made for such end users. They can download the Java RE themselves from the web, or software vendors can include it in their own products. The typical end-user doesn't need the bulkier Java 2 SDK with its development tools.

## Links

Download -- Download page from which you can obtain version 1.4.2 of both the Java 2 SDK and the JRE.

J2SE 1.4.2 Platform Documentation -- Table of contents for the J2SE 1.4.2 platform documentation, with links to API specifications, user guides, tool documentation, and more.

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