Naked Singles Technique

Naked singles is the most basic and easiest Sudoku technique to learn. A naked single occurs when an empty cell can only be filled by one possible number.

This happens when the cell's row, column, and 3×3 box collectively contain 8 out of the 9 numbers (1-9), leaving only one number as a possibility. It's "naked" because the single candidate is visible without needing to eliminate other possibilities first.