A chassis consists of an internal vehicle frame that supports an artificial object in its construction and use, can also provide protection for some internal parts. An example of a chassis is the underpart of a motor vehicle, consisting of the frame.
In an electronic device, the chassis consists of a frame or other internal supporting structure on which the circuit boards and other electronics are mounted.
 
It can either be used in skid steel configuration  or differential configuration. The body contains perforated holes for easy mounting of various size circuit boards and other mechanical components.
 
This Chassis board is widely used as a mechanical frame structure of mobile robots. It is the backbone of the robot, where we arrange and connect everything like motors, sensors, and wheels. It gives you the base to build our robot and allows you to place your components according to requirements.