F2L 21
The algorithm, how to recognise it and how to practise it without cheating.
Recommended algorithm
R U' R' U2 R U R'7 moves · R and U only
Alternatives
U2 R U R' U R U' R'8 moves · R and U onlyU2 R U R' U2 R U2 R'8 moves · R and U onlyU2 F' U' F R U R'7 moves
How to recognise it
White on top, corner above the slot; the edge is on the left, its top colour matching the corner's right sticker.
Practise 21 now
Random-state scrambles, a timer and spaced review. Free, on the web and on your phone.
Other cases: Separated on top
5
U' R U R' U2 R U' R'Separated on top · 1/386R' U' R F R' F' U RSeparated on top · 1/387U' R U2 R' U2 R U' R'Separated on top · 1/388R2 U2 F R2 F' U2 R2Separated on top · 1/389U' R U' R' U F' U' FSeparated on top · 1/3810U' R U R' U R U R'Separated on top · 1/3819U R U2 R' U R U' R'Separated on top · 1/3820U' F' U2 F2 R' F' RSeparated on top · 1/3822U2 R U R' F' U' FSeparated on top · 1/38