A Stock Puzzle that presents a grid, and a bunch of elements that must be put in appropriate cells of the grid. There are usually constraints in which elements must or cannot be placed in the same rows, in the same columns, in the same diagonals, or touching on certain cell boundaries. The constraints may or may not determine a unique solution. Usually the grid is square, but it need not be quadrilateral; it could even have irregular boundaries. Examples of Grid Puzzle include: