What are the shading techniques called?

Circulism: Used to shade a base layer on the hand to give it a consistent base texture.

Contour Shading: Used to shade stretched skin.

Hatching: Used to shade nails and stretched skin.

Cross Hatching: Used to create patterns in the skin and to emphasize deep valleys/crevices.

i think it's but if you get it wrong its not my fault : )