| # Introduction to the Java Runtime Environment including Java Plug-in | Documentation Contents

On Windows, a separate Java 2 Runtime Environment including Java Plug-in is installed with the SDK such that Internet Explorer and Netscape Navigator will use this plug-in when encountering special HTML pages that invoke it. On Solaris, you can obtain this plug-in separately. The following section describes how to configure your HTML pages to invoke the plug-in.

- What is the Java Plug-in?
- How is the JRE/Plug-in Available and Installed?
- How is the Plug-in Invoked From an HTML Page?
- How to Modify your HTML

## What is the Java Plug-in?

> The Java 2 Runtime Environment including Java Plug-in is a Sun product that is composed of two parts: The Java 2 Runtime Environment and the Java Plug-in.

> The Java 2 Runtime Environment is the Java platform on which you can run, test and ship your own applications. It consists of the Java virtual machine, the Java platform core classes, and supporting files. It contains no development tools -- no compiler, debugger, or other tools. The Runtime Environment requires additional software -- the Java Plug-in -- to enable it to run applets in a browser.

> The Java Plug-in software allows Java applets and JavaBeans components to run in a browser using Sun's Java Runtime Environment, instead of the browser's default Java runtime. The Java Plug-in works with Netscape Navigator and Microsoft Internet Explorer. The plug-in requires special `<OBJECT>` and `<EMBED>` tags be embedded in the HTML page. For documentation on the Java Plug-in, see Java Plug-in and click on "Documentation". An extensive Java Plug-in FAQ is available.

## How is the Runtime Environment and Plug-in Available and Installed?

> The Java 2 Runtime Environment including Java Plug-in is available from Sun on both Windows and Solaris:

> - The Windows version of the Java 2 SDK includes a redistributable version of the Java 2 Runtime Environment including Java Plug-in, which plugs into a browser, upgrading the browser to the Java 2 platform. Once you install it, you will see that the "Java Plug-in control panel" has been added to your Windows "Start" menu under "Programs".

> - The Solaris version is downloaded separately from the SDK Reference Implementation. For more information, see Sun's Java Plug-in website.
> While the Java 2 Runtime Environment including Java Plug-in is installed with the SDK for Windows, it is a separate product and is redistributable with your application, applet or JavaBean components subject to the terms and conditions of its software license (found in the Runtime Environment's README and LICENSE files).

> Note that the SDK has its own internal, complete, non-redistributable Java runtime environment in the `jre` subdirectory. This is the runtime environment used by the SDK tools (javac, javadoc, appletviewer, and so forth) and is not to be confused with the redistributable Java 2 Runtime Environment/Plug-in.

## How is the Java Plug-in Invoked From an HTML Page?

> As always, the browser's built-in Java runtime will be used when it encounters an `<APPLET>` tag. However, once the plug-in is installed, it will automatically load the Java Runtime Environment when it hits a page with special `<OBJECT>` and `<EMBED>` HTML tags. The browser can then load Java 2 Platform-based applets from this page to make full use of Java 2 Platform-based features. For details on how to configure your HTML pages to invoke the JRE, see the next section.

## How to Modify HTML Pages

> The plug-in requires the `<OBJECT>` tag enclose the `<EMBED>` tag to work in both Internet Explorer and Netscape Navigator. For details on how to configure your HTML pages to invoke the Java 2 Runtime Environemnt, go to Sun's Java Plug-in website, choose "Documentation", then "Java Plug-in HTML Specification".

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