Normal difficulty — the level many solvers call medium sudoku — is where Sudoku begins to reveal its real depth, and where many players discover their favourite level to play. These puzzles suit solvers who are comfortable with basic scanning and want a genuine challenge without venturing into advanced territory. Elimination and scanning will carry you a good distance into the grid, but at some point the easy cells will run out and you will need a more deliberate approach. The most important technique to learn here is naked pairs: when two cells in the same row, column, or 3×3 box share exactly the same two candidate digits — and only those two — you can safely remove those candidates from every other cell in that group. Finding a naked pair often unlocks a chain of simple deductions that fills several cells at once. Before applying this technique, get into the habit of writing all possible candidates in small pencil marks inside each empty cell. Without a clear record of which digits are still available in each cell, naked pairs are almost impossible to spot. Update your candidate list every time you fill in a new digit: cross out that digit from all cells in the same row, column, and box. Normal puzzles typically take 20 to 40 minutes and reward methodical, unhurried thinking above all else.