As research progresses in distributed robotic systems, more and more aspects of multirobot systems are being explored. This article describes advances in multirobot systems, and surveys the current state of the art. The focus is principally on research that has been demonstrated in physical robot implementations. I have identified eight primary research topics within multirobot systems—biological inspirations, communication, architectures, localization/mapping/exploration, object transport and manipulation, motion coordination, reconfigurable robots, and learning—and discuss the current state of research in these areas. As I describe each research area, I identify some key open issues in multirobot team research, and conclude by identifying several additional open research issues in distributed mobile robotic systems.