Mirrored from Sudopedia, the Free Sudoku Reference Guide
The Naked Single is categorized as a solving technique but you can hardly call it a technique. A naked single is that what remains after you have applied your solving techniques, by eliminating other candidates.
The easiest way to find naked singles in the grid is using pencilmarks. Cells with a single pencilmark are easy to spot. Without pencilmarks, you need to inspect the peers of the cell and see if there is only a single digit missing in the peers. You need a good short-term memory to do it this way, but many players prefer to solve easy Sudokus without pencilmarks.
The following Sudoku has two Naked Singles for digit 8.