What is a good voltage?

Excuse me, could you please elaborate on what constitutes a "good voltage"? I understand it's a measure of electric potential difference, but in what context are we discussing it? For instance, is it in relation to powering household appliances, industrial machinery, or perhaps electronic components within a cryptocurrency mining rig? Each scenario would have its own optimal voltage range, so clarity on the specific application would be invaluable. Thank you for your time.