A logic puzzle is made of a grid and a list of clues. The grid will show a number of categories and a number of items in each category. Each item can only be matched with one other item in each of the categories. The puzzle has only one unique solution that can be found by using the clues given and logic alone. Xs and Os are used as true and false markers. You put an X in a spot where something can never be true and an O where something is proven true.