Final answer:
The basic novel feature of hysteresis is that the reaction of a system to changes is dependent on its past behavior. In a ferromagnetic material, this is seen as a characteristic loop on hysteresis graph, showing a lag in the magnetization response to a changing external magnetic field, labeled as magnetic hysteresis.
Step-by-step explanation:
The basic novel feature of all hysteresis is the behavior of a system in which the reaction of the system to changes is dependent upon its past responses to change. In the context of a ferromagnet described in your example, this means that the material's magnetization will follow a certain path when an external magnetic field (B0) is applied and then will follow a different path when the field is reversed. This path is depicted as a loop on the hysteresis graph. Initially, as the ferromagnetic material is magnetized, it follows a curve from point 0 to point a. When B0 is reversed, the magnetization moves along the curve from a to b. If B0 is reversed again, the material doesn't return to point 0 directly but follows the curve from b back to a, showing a lag in response, known as magnetic hysteresis. This effect is intrinsic in ferromagnetic and some other materials, reflecting a history-dependent behavior.