U - upper, R - right, L - left, F - front, D - down, B - back. Each move is done by turning that side clockwise 90 degrees while facing that side.
A letter with a prime (') means to turn that side counterclockwise 90 degrees.
A letter with a 2 means to turn that side 180 degrees or face 90 degrees twice.
Wide moves are denoted by a lower case letter. They turn 2 layers at once.
Entire cube rotations are written as x, y and z.
Slice moves are written as M, E and S and turn the middle layer of the cube. M follows the L direction, E follows the D direction, S follows the F direction.