Allosteric Site:This is the 'switch' in our analogy - it's where a molecule that is not a substrate may bind and change the shape of an enzyme, affecting its ability to function.
Inhibitor:This acts like something blocking access to your light switch. It's a substance that slows down or stops an enzyme's activity.
Activator:This would be like someone helping you reach a high light switch. It's a substance that increases the activity of an enzyme.