[1] Its components include the Player network server and the Stage platform robotics simulators.
Although accurate statistics are hard to obtain, Player is one of the most popular open-source robot interfaces in research and post-secondary education.
The project was founded in 2000 by Brian Gerkey, Richard Vaughan and Andrew Howard at the University of Southern California at Los Angeles, and is widely used in robotics research and education.
The Player is set of application programming interfaces (APIs, e.g., position2d, bumper, ir, speech, power) that can be implemented by a robot chassis (Roomba, Khephera, etc.
Gazebo integrated the Open Dynamics Engine (ODE) physics engine, OpenGL rendering, and support code for sensor simulation and actuator control.