Via the Adobe Exchange, Adobe allows developers like you and I to create plug-ins for their products, and upload them for sale. Users may download hundreds of extensions, functions, code, etc.

There are Exchanges by products such as Acrobat Connect, Adobe Captivate, After Effects, Bridge, ColdFusion, Director, Dreamweaver, Fireworks, Flash, Flash Lite, Flex, GoLive, Illustrator, InDesign, Photoshop, Pocket PC, and RoboHelp Skins.

In order to install an extension, you must use the Adobe Extension Manager. Simply download the Extension Manager to your hard drive and run it to install it.

The Adobe Exchange allows you to search from among thousands of uploads.

Then once you've found an extension you desire to install, follow their installation instructions, which typically consist of clicking their .MXP file to install it.

Once you open a document in Flash, from the Window | Other Panels menu items, you may now see the new extension you've added, in our case, the EnvisionDemo.

If you open the Adobe Extension Manager, you'll now see the new extension added to the list. You also have the ability to Disable, Package, Submit, and Remove Extensions.