Nonograms, also known as Japanese puzzles, are logic puzzles and were invented by the designer Non Ishida.
The game consists of a grid of any number of cells (e.g. 10 × 10 or 10 × 15). The aim is to color (or not color) the cells of a grid in such a way that the colored boxes in each row and column correspond to the specified number and structure.
For example, the number sequence “4 2 1” before a row contains the information that a block of four contiguous cells, a block of two contiguous cells and a single cell are to be colored in this order in this row (with at least one box between them).
A (usually unambiguous) solution can be logically derived from the combination of row and column information.