Definitions

Here is a list of terms used throughout this website and also in the help panels of the SuDoku Solver.

 Grid
 The whole SuDoku, made up of 81 Squares arranged in a 9 x 9 grid.

 Row
 Nine adjacent horizontal Squares in which the numbers 1 to 9 each occur only once.

 Column
 Nine adjacent vertical Squares in which the numbers 1 to 9 each occur only once.

 Box
 Nine Squares arranged in a 3 x 3 grid in which the numbers 1 to 9 each occur only once. There are nine Boxes in the whole SuDoku Grid.

 Segment
 Three adjacent Squares arranged either horizontally or vertically that are all in the same Row and Box, or in the same Column and Box.

 Possible
 The possible solutions for each Square. Initially, all the numbers 1 to 9 may be Possibles in a particular Square until they are eliminated by the action of various Analyses. Eventually there is only one Possible left and that becomes the Solution for that Square.

 Pair
 A Square which has only two remaining Possibles. The starting point for the Splits Analysis.

 Contradiction
 Two or more Squares in the same Row, Column, or Box that have the same Solution. Or a Square with no Solution and no Possibles.