Gyroscopes are devices used for measuring orientation based on the principle of angular momentum. There are a lot of types gyroscopes used in present day technology. The most used devices are MEMS where you can measure angular positions precisely. These devices are most useful in flying objects where a small change in position can cause a lot of difference or devastation and is also used where you need to measure the position and use it as an input to feedback systems or control systems. Applications of gyroscopes also include inertial navigation systems where magnetic compasses would not work (as in the Hubble telescope) or would not be precise enough (as in intercontinental ballistic missiles). These gyroscopes are a must for UAV’s because they are autonomous.