This interactive piano app renders a two-octave keyboard as an SVG, where clicking a key triggers a sine-wave tone. The React component manages a set of pressed keys, updating their visual state, while the Web Audio API's `createOscillator`, `createGain`, and `exponentialRampToValueAtTime` methods synthesize a short, fading note. The white and black keys are drawn as SVG rectangles with note labels, and the app uses CSS transitions to show a subtle press effect.