D

D[f,x] gives the partial derivative ∂f/∂x. 

D[f,{x,n}] gives the multiple derivative ∂nf/∂xn.

D[f,x,y,…] gives the partial derivative ⋯ (∂/∂y)(∂/∂x) f.

D[f,{x,n},{y,m},…] gives the multiple partial derivative ⋯ (∂m/∂ym)(∂n/∂xn) f.

D[f,{{x1,x2,…}}] for a scalar f gives the vector derivative (∂f/∂x1,∂f/∂x2,…). 

D[f,{array}] gives an array derivative.

Please visit the official Wolfram Language Reference for more details and examples on core symbols.