Robot Operating System (ROS) is a collection of software frameworks for robot software development, providing operating system-like functionality on a heterogeneous computer cluster.
These are very handy. They are simple angle brackets with one threaded and unthreaded hole. Use them for connecting PCBs at 90 degree angles, mounting accelerometers, gryros, etc. They can also be used on the universal plate set for mounting all sorts of sensors and such.