Of all of the traditional musical instruments, rigorous scientific and engineering principles have been applied most comprehensively to the modern piano. This presentation will explore some of the main aspects of the design compromises and developments that have been implemented in all commercial piano designs since the late 19th century. The focus will be particularly upon the scientific details of sound production by pianos and how pianos have been engineered to exploit the principles of acoustics, dispelling some common misconceptions along the way. The intended audience is pure and applied scientists and engineers interested in design evolution, and musicians interested in how science and engineering have influenced instrument design. A basic knowledge of physics (frequency, Fourier series basics, tension, stretched strings, impedance, power transmission, elasticity, 1D wave equation) and only a little music theory (names of notes, intervals, basic notes on a stave) will be assumed.