Cube anatomy
Centres, edges and corners: what moves where, and why you solve pieces rather than stickers.
A 3x3 has 26 visible pieces. The six centres are fixed to the core and never move relative to each other: they define each face's colour. The 12 edges have two stickers, the 8 corners three. A turn moves whole pieces, never stickers on their own, so an edge is always an edge and the white-red edge always shows white and red.
Solved. White opposite yellow, green opposite blue, red opposite orange (the standard scheme).
Edges only: the 12 two-coloured pieces.
Corners only: the 8 three-coloured pieces.
Because centres fix the colours, 'solved' means every piece is in the slot between the centres of its colours, the right way round. Bigger cubes add inner edges and centre pieces that do move; the 2x2 has only corners, so any face can be the first.
- •Layer: a slice of 9 pieces (top, middle, bottom...). F2L means the bottom and middle layers.
- •Slot: an F2L position, a bottom corner plus the middle edge above it (front-right, front-left, back-left, back-right).
- •Block: a group of solved pieces that fit together, like Roux's 1x2x3 blocks.