Derivative

Derivative(n)[f]

represents the n-th derivative of the function f.

Derivative(n1, n2, n3,...)[f]

represents a multivariate derivative.

>> Derivative(1)[Sin]
Cos(#1)&

>> Derivative(3)[Sin]
-Cos(#1)&

>> Derivative(2)[# ^ 3&]
6*(#1&)

Derivative can be entered using ':

>> Sin'(x)
Cos(x)

>> (# ^ 4&)''
12*(#1^2&)

>> f'(x) // FullForm
"Derivative(1)[f][x]"

The 0th derivative of any expression is the expression itself:

>> Derivative(0,0,0)[a+b+c]
a+b+c

Unknown derivatives:

>> Derivative(2, 1)[h]
Derivative(2,1)[h]

>> Derivative(2, 0, 1, 0)[h(g)]
Derivative(2,0,1,0)[h(g)]