ROS is an open-source, meta-operating system for your robot. It provides the
services you would expect from an operating system, including hardware
abstraction, low-level device control, implementation of commonly-used
functionality, message-passing between processes, and package management. It
also provides tools and libraries for obtaining, building, writing, and running
code across multiple computers. ROS is similar in some respects to 'robot
frameworks', such as Player, YARP, Orocos, CARMEN, Orca, MOOS, and Microsoft
Robotics Studio.

The ROS runtime "graph" is a peer-to-peer network of processes that are loosely
coupled using the ROS communication infrastructure. ROS implements several
different styles of communication, including synchronous RPC-style
communication over services, asynchronous streaming of data over topics, and
storage of data on a Parameter Server. These are explained in greater detail in
our Conceptual Overview.

ROS is not a realtime framework, though it is possible to integrate ROS with
realtime code. The Willow Garage PR2 robot uses a system called pr2_etherCAT,
which transports ROS messages in and out of a realtime process. ROS also has
seamless integration with the Orocos Real-time Toolkit.

Homepage:
http://www.ros.org/wiki/ROS
