The use of hand gesture interfaces to control computer games, robots, medical visualization devices and crisis management systems allows an expressive, natural and intuitive way of interaction. However, in order to successfully implement hand gesture systems for diverse everyday environments, significant technical and usability challenges must be overcome. Such systems should have; fast response times, high recognition accuracy, ease of learning and a high degree of user satisfaction. These issues are discussed here with an emphasis on machine vision techniques This paper presents a state-of-the-art review of real-world applications. These include four areas in which hand gesture interfaces show the fastest advances: health environments and assistive technologies, entertainment, crisis management/disaster relief systems, and human-robot interaction. Although the use of hand gestures in games and virtual reality environments is a popular form of interaction, such interfaces require more development before additional deployment can be expected. This review highlights the potential of gestures as a natural modality for human-machine interaction, and indicates the need for additional research and evaluation procedures for such interfaces to gain widespread acceptance.