Active Worlds is a collection of online virtual spaces, developed by ActiveWorlds Inc. and launched on June 28, 1995.
Access to Active Worlds is free; just download and install the browser application, become a 'citizen' by creating a free user account, and start exploring. The Active Worlds browser includes basic web browsing, voice chat, and instant messaging. Users can customize their own avatar and build in several public building worlds. Purchasing in-world credits lets users purchase additional accessories for their avatar, or to run their own personal worlds for which they can develop their own custom 3D content.
The largest public building world, Alphaworld, is the largest space in Active Worlds, approximately equivalent in area to California, and is also probably the Internet's longest lived multi-user online 3D environment, having been in continuous operation since 1996.
Active Worlds building system is based on each world having a library of 3D models, texture images, sounds, avatars, and other assets. Builders create copies of existing objects and re-position them, and can then apply modifications to their appearance and behaviour using scripted commands.