Naked Pair Walkthrough

A Naked Pair is two cells in the same unit that hold the same two candidates and nothing else. Those two digits are locked into those cells, so they can be removed from every other cell in the unit.

Sudoku board with pencil-mark candidates before applying the Naked Pair technique
Before — candidates pencilled in. There is a Naked Pair in Block 2.

There is a Naked Pair in Block 2. Applying the Naked Pair eliminates 2 candidates and solves 1 cell (struck out in red below; any solved cells shown in green).

The same Sudoku board after the Naked Pair technique eliminates 2 candidates and solves 1 cell
After applying the Naked Pair.