Up and Down Faces

The same logic applies to the Up (U) and Down (D) faces.

Imagine looking down from above: U is the top layer clockwise, D is the bottom layer clockwise.
Remember: clockwise always means «as seen when looking directly at that face».

U Up face clockwise 90°
Keep the lower two layers steady and turn the top layer. Turn clockwise as seen while looking directly at that face. This is only an optional grip tip — use any comfortable method.
U' Up face counter-clockwise 90°
Keep the lower two layers steady and turn the top layer. Turn counter-clockwise as seen while looking directly at that face. This is only an optional grip tip — use any comfortable method.
U2 Up face 180°
Keep the lower two layers steady and turn the top layer. Make a 180° half turn; either direction is fine. This is only an optional grip tip — use any comfortable method.
D Down face clockwise 90°
Keep the upper two layers steady and turn the bottom layer. Turn clockwise as seen while looking directly at that face. This is only an optional grip tip — use any comfortable method.
D' Down face counter-clockwise 90°
Keep the upper two layers steady and turn the bottom layer. Turn counter-clockwise as seen while looking directly at that face. This is only an optional grip tip — use any comfortable method.
D2 Down face 180°
Keep the upper two layers steady and turn the bottom layer. Make a 180° half turn; either direction is fine. This is only an optional grip tip — use any comfortable method.