D effectively threads D over each element of list.
D is equivalent to D where {list} is repeated n times. If f is a scalar, and list has depth 1, then the result is a tensor of rank n, as in the n term of the multivariate Taylor series of f.
D is normally equivalent to First[Outer[D, {f}, list1, list2, ...]].
If f is a list, then D effectively threads first over each element of f, and then over each element of list. The result is an array with dimensions Join[Dimensions[f], Dimensions[list]].
Numerical approximations to derivatives can be found using N.
D uses the chain rule to simplify derivatives of unknown functions.
D can be input as . The character , entered as Esc , Esc, can be used instead of an ordinary comma. It does not display, but is still interpreted just like a comma.