The pedals on a piano are used to change the tone of the piano in various ways. Modern acoustic or digital pianos usually come with three pedals, while older acoustic pianos have two. Here is a summary of the three pedals on a grand piano, from left to right:

1. Una corda pedal: This pedal is also known as the soft pedal. When pressed, it shifts the entire keyboard and action slightly to the right so that the hammers do not strike all of the strings. This creates a softer, duller tone as opposed to the normal bright tones.

2. Sostenuto pedal: This pedal is a selective damper. When pressed, it holds up only those dampers that have been raised by their keys, sustaining only the notes that are depressed when the pedal is activated.

3. Damper pedal: This pedal is also known as the sustain pedal. When pressed, it lifts all of the dampers off the strings, allowing all of the strings to vibrate sympathetically and prolonging the sound of the piano.

The proper technique for using the pedals depends on the piece of music being played, and some composers are clear where they intend the pedals to be used. Beginners need not worry too much about the pedals, as their use is a relatively advanced technique.