Polyominoes are geometric shapes formed by connecting one or more equal-sized squares edge to edge. The simplest polyomino is a monomino, which consists of a single square. As more squares are added, they create different types of polyominoes, such as dominoes (two squares), trominoes (three squares), and tetrominoes (four squares). These shapes are often used in puzzles and games, such as Tetris, where players manipulate tetrominoes to fill rows. Polyominoes can be classified based on the number of squares they contain, leading to various configurations and arrangements that can be explored in mathematics and recreational activities.