A stress ball or hand exercise ball is a malleable toy, usually not more than 7 centimetres (2.8 in) in diameter. It is squeezed in the hand and manipulated by the fingers, ostensibly to relieve stress and muscle tension or to exercise the muscles of the hand.
Despite the name, many stress balls are not spherical. Some are molded in amusing shapes, and pad- or transfer-printed with corporate logos. They may be presented to employees and clients of companies as promotional gifts. Because of the many non-spherical shapes now available, stress balls are generically known as stress relievers.