Nonogram is picture logic puzzles in which cells in a grid must be colored or left blank according to numbers at the side of the grid to reveal a hidden pixel art-like picture.
In this puzzle type, the numbers are a form of discrete tomography that measures how many unbroken lines of filled-in squares there are in any given row or column. For example, a clue of "4 8 3" would mean there are sets of four, eight, and three filled squares, in that order, with at least one blank square between successive sets.