A sliding puzzle is a type of puzzle that consists of a frame containing a grid of numbered tiles, with one empty space. The objective is to arrange the tiles in a specific order by sliding them into the empty space. The most common version is the 15-puzzle, which has a 4x4 grid and features tiles numbered from 1 to 15. Players can only move tiles adjacent to the empty space, making strategic planning essential. Sliding puzzles can vary in size and complexity, and they are often used as brain teasers to improve problem-solving skills and spatial reasoning.