What are degrees of Freedom in the Lagrangian/Hamiltonian formulation of classical mechanics? I've been getting very confused trying to understand this concept. Would six degrees of freedom mean up, down, left, right, back & forward? I've seen it said that 3 degrees of freedom mean the x, y & z axes, so my above sentence is really only 3 degrees of freedom, is it? Then, I seen the Susskind classical mechanics lecture claim there are 6 degrees of freedom, x, y & z axes & then position, velocity & acceleration. But, then I read in a previous physicsforums post the claim that velocity & acceleration are not dimensions ergo they are not degrees of freedom! The wikipedia article is not in the least helpful & I've tried to watch the nptelhrd lectures to only get more confused. What does it mean to have a degree of freedom constricted also? Thanks it would be really helpful for somebody to shed some light on this idea for me.