Active Worlds (AW) is a 3D web browser for Microsoft Windows. It allows users to assign themselves a unique name, log into the Active Worlds universe, and explore worlds and places that other people have built.

The program's original goal was to be the 3D equivalent to a 2D browser such as Internet Explorer or Mozilla, where instead of websites, the user could construct an office and display their products in 3D, or build an art gallery and hang the pictures on the wall. However in recent years the program has shifted its attention to more of an art orientated program, in adding features for building.