The "Instructions" button leads to some basic help pages that explain the use of the various functions invoked with the function keys...or by the icons at the left of the puzzle display. It may not be very useful to a novice Sudoku puzzle solver, but will prove very useful after you have gained a little familiarity with the puzzles and this program.

We will soon be adding a "Tutorial" button which will give a much more detailed explanation...and helpful to new solvers...of how to solve puzzles at various levels of difficulty.