This paper explores the formation, development, and research status of virtual geographic environments (VGE), and discusses the concept of VGE in terms of virtual reality theory and techniques. A virtual geographic environment (VGE) is defined as a shared virtual space into which digital geographic objects and environments, as well as 3-D avatars, representing users or people in the physical environments, are transplanted. The characteristics of VGE are addressed from aspects of basic thoughts, system structure, and level of social organization of online participants. VGE systems include five kinds of spaces, namely Internet space, data space, 3-D representation space, personal perceptual and cognitive space, and collaborative and social space. In view of online users, a VGE could be taken as an experimental laboratory or a system tool to deal with geo-scientific problems while the number of users is less, or as a virtual space or worlds in which numerous users are living and working. The relationship and differences among GIS, digital earth, and VGE are scrutinized, too. It is argued that VGE systems stem from the ultimate development of GIS and cartography, and are prototypes of Google Earth, Virtual Earth, EDUSHI, E-Urban，and Second Life. The key techniques, development of system platform, applications，and outlook of VGE are presented in terms of data, modeling, representation, and collaboration. The paper puts forward a fundamental theoretical framework of VGE from aspects of geographic philosophy and geographic sciences, and discusses issues related to human oriented geographic information sciences, VGE based geographic scientific methodology, and computing man-land relationship.