A sliding puzzle, sliding block puzzle, or sliding tile puzzle is a combination puzzle that challenges a player to slide (frequently flat) pieces along certain routes (usually on a board) to establish a certain end-configuration. The pieces to be moved may consist of simple shapes, or they may be imprinted with colours, patterns, sections of a larger picture (like a jigsaw puzzle), numbers, or letters.
The fifteen puzzle has been computerized (as puzzle video games) and examples are available to play for free on-line from many Web pages. It is a descendant of the jigsaw puzzle in that its point is to form a picture on-screen. The last square of the puzzle is then displayed automatically once the other pieces have been lined up.