OLL 3
The algorithm, how to recognise it and how to practise it without cheating.
Recommended algorithm
f R U R' U' f' U' F R U R' U' F'13 moves
Alternatives
(U) r' R2 U R' U r U2 r' U M'11 moves
How to recognise it
A dot with one yellow corner on top. Hold that corner at front right: the front side shows yellow only on its edge.
Its inverse is another case
Do the 3 algorithm backwards, F U R U' R' F' U f U R U' R' f', and you are solving 4.
That's why CubeDojo never scrambles 3 that way: it builds a random state with the case fixed, so you practise 3 and not 4.
Practise 3 now
Random-state scrambles, a timer and spaced review. Free, on the web and on your phone.