A PLAYER piano is a type of piano that can be played without a pianist. It is operated by a mechanism that plays the piano using perforated paper rolls. UPRIGHT pianos are the most common type of piano and are designed to stand vertically against a wall. SPINET pianos are smaller than UPRIGHT pianos and have shorter strings, resulting in a less powerful sound. GRAND pianos are the largest type of piano and have longer strings, producing a fuller sound. All of these types of pianos are kinds of pianos.