CFOP step 4: 2-look PLL, finish the cube

The top is all yellow. PLL means permuting the last layer: moving the top pieces to their places without turning them. Full PLL has 21 algorithms. 2-look PLL uses 6:

Place the corners: A-perm or Y-perm.
Place the edges: Ua, Ub, H or Z.

M' U M2 U M2 U M' U2 M2 U'

Z-perm: two pairs of neighbouring edges swap

First look: the corners

Look at the top row of each side for headlights: two corner stickers of the same colour on one side.

Headlights on one side: A-perm

The algorithm from the beginner method. Put the headlights at the back and do it once. Then turn the top: the corners all line up.

R' F R' B2 R F' R' B2 R2

A-perm: R' F R' B2 R F' R' B2 R2

No headlights anywhere: Y-perm

Two diagonally opposite corners need to swap. The Y-perm does it from any angle, then turn the top to line the corners up. It's long, so learn it in two halves: F R U' R' U' R U R' F', then R U R' U' R' F R F'.

F R U' R' U' R U R' F' R U R' U' R' F R F'

Y-perm: F R U' R' U' R U R' F' R U R' U' R' F R F'

Headlights on all four sides

The corners are already in place. Turn the top to line them up and go to the edges.

Second look: the edges

The corners are in place. Look at the middle sticker of each side's top row.

One side solved: Ua or Ub

Put the solved side at the back. If the front edge needs to go right, do Ua. If it needs to go left, do Ub. Both are from the beginner method.

R U' R U R U R U' R' U' R2

Ua: R U' R U R U R U' R' U' R2

R2 U R U R' U' R' U' R' U R'

Ub: R2 U R U R' U' R' U' R' U R'

No side solved, opposite edges swap: H-perm

Every edge sits opposite where it belongs: the front edge has the back colour, and so on. The H-perm uses M, the middle slice, and works from any angle.

M2 U M2 U2 M2 U M2

H-perm: M2 U M2 U2 M2 U M2

No side solved, neighbouring edges swap: Z-perm

Each edge belongs on a side next to it. Hold the cube so the front edge belongs on the left: then the left edge belongs at the front, and the right and back edges swap too.

M' U M2 U M2 U M' U2 M2 U'

Z-perm: M' U M2 U M2 U M' U2 M2 U'

No time to learn H and Z yet? Do Ua with any side at the back. One side becomes solved, and you finish with Ua or Ub.

Common mistakes

Headlights at the front. The A-perm needs them at the back.
Turning the top between the two looks. That's fine, and often needed: line the corners up first, then read the edges.
Slice moves the wrong way. M turns like L: the front column goes down. M' goes up.