Given Cell
A digit pre-placed in the puzzle's initial state. Players cannot modify these cells.
A given (also called a clue) is a digit already placed on the grid at the start of the puzzle. Players cannot change these digits and must logically fill in the remaining empty cells. The number and placement of givens determine the puzzle's difficulty.
Relationship Between Givens and Difficulty
Generally, more givens make a puzzle easier. Easy puzzles have 36-45 givens, Medium 30-35, Hard 26-29, Expert 22-25, and Master/Extreme 17-23. However, the number of givens alone does not determine difficulty; the placement pattern is equally important.
Minimum Number of Givens
It was proven in 2012 that the minimum number of givens for a Sudoku puzzle with a unique solution is 17. With 16 or fewer givens, a unique solution cannot be guaranteed. Approximately 49,000 puzzles with exactly 17 givens have been discovered.