The ROS framework provides the Unified Robot Description Format (URDF), which is an XML file format that describes a robot, its geometry, its parts, its joints, physics, and so on. Whenever we use a 3D robot on ROS, for example, a mobile robot (Turtlebot), the humanoid robot (PR2), and some types of aerial robot, a set of several URDF files must be associated with them.

In the following sections, we will learn how to use the URDF file format to create a 3D model of a real-world robot for development.