Centers Never Move

Look at the center sticker of each face. There are exactly six centers, one per face — and they never move when you turn any face.

This is the most important fact about the cube: because centers are fixed, each face's color is decided by its center. You cannot move the white center to where the green center is.

So 'solving the white face' always means 'around the white center' — the center tells you where each face belongs.