Why you should not PARTIALLY press the Clutch?

In manual transmission cars, some drivers partially press down on the clutch pedal to make the engine operate more smoothly. Some drivers even have the habit of resting their foot on the clutch pedal. This is known as ‘riding’ the clutch. However, do you know that this habit is really bad for your car? This video illustrates the physics behind 'riding the clutch' and its consequences in a logical manner.