World Wind is a collection of components that interactively display 3D geographic information within Java applications or applets. Applications and applets use World Wind by placing one or more WorldWindow components in their user interface. The World Wind components are extensible. The API is defined primarily by interfaces, so components can be selectively replaced by alternative components. In typical usage, applications associate a Globe and several Layers with a Model They then pass that model to a SceneController that displays the globe and its layers in a WorldWindow. The scene controller subsequently manages the display of the globe and its layers in conjunction with an interactive View that defines the user's view of the planet. The objects implementing the above interfaces may be those provided by World Wind or those created by application developers. Objects implementing a particular interface may be used wherever that interface is called for. World Wind provides several Globe objects representing Earth, Mars and the Earth's moon, and provides basic implementations of Model, SceneController and View.