The sustain pedal, is on the right, whether your piano has 2 pedals or 3 pedals. Sometimes it is referred to as simply ‘the pedal’ because it is used so much more frequently than the left pedal (known as the soft pedal) or the middle pedal ( which is only found on some pianos).
As the name suggests, the sustain pedal can sustain the sound of the strings so much longer than if it was not used at all. This is because the pedal causes all the dampening felts inside the piano to be moved away from the strings, so that when you let go of a note, its dampener doesn’t return to resting against the internal strings. It sould probably more aptly called ‘the pedal that prevents the artificial stopping of the string vibrating by the felt dampener’, but this name is far too long and it would never stick.
The whole purpose of the pedal is to make sure that each note is blended seamlessly into the next. This is particularly useful when you are playing a piece of music and you are using the notes of a particular chord, spread out over one or two bars, the pedal really makes the notes and the phrase sound really wonderful. The sustain pedal is also useful for those times when one hand (usually the left hand), has to leap smoothly from one note to another that are beyond the stretch of an average sized hand. In this circumstance, it does created the desired blended effect beautifully.
The sustain pedal, unfortunately, is often over used by inexperienced piano players and piano students as a tool to cover up mistakes or bad technique. I most certainly did this frequently when I was a piano student and I regret doing it as much as I did because I thought it was a short cut to sounding better, when really the supposed short cut actually slowed my progress down.
As I have already stated, the sustain pedal can be used as an attempt to cover up mistakes or flaws in technique. The fact of the matter is that it doesn’t actually conceal flaws at all and it can really make the piano music sound very murky and muddy.
Here’s what I think should happen with regards to using the sustain pedal. Firstly, it is always better to under use the pedal than overuse, so you can avoid having your music sounding all muddy. Secondly, I would recommend learning to play a new piece of piano music well before putting in the pedaling. By doing this, you can hear your mistakes or weaknesses much clearer without the pedal and fix those parts up before adding the pedal part into the music.
I understand that some older people might have some issues with flexing their foot up and down to press the pedal, so if this is an issue for you, then skip using the pedal altogether because while playing the piano with the sustain pedal can enhance your piano playing, it is not actually essential for playing the piano. It is indeed possible to play the piano well without using the pedal at all.