Limbs were important appendages of organic bodies and many types of mechanical chassis. They were typically designed for motion and/or manipulation, and were found on most sentient and non-sentient species throughout the galaxy, and many droids and other artificial constructs. Humans and many other important sentient species were bipedal, with two legs and two arms, and this form was imitated by many droids; but there were many variations. Sometimes these were relatively subtle, especially in the construction of hands, feet and their digits.