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.

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.