A halo is a circle of light that appears around something, most famously shown in religious art as a glowing ring above the heads of angels and saints. Artists used halos to show that a person was holy or divine. If you look at old paintings in a museum, you'll often see golden halos floating above the heads of important religious figures.

In nature, you can sometimes see a halo around the sun or moon when ice crystals high in the atmosphere bend the light, creating a glowing ring. Photographers call the blur of light around a bright object in a photo a halo effect.

People also use halo to describe the special glow of goodness or innocence around someone. When someone seems perfect or can do no wrong in others' eyes, we might say they have a halo. A teacher's favorite student might seem to have a halo, at least until they get caught passing notes in class.

The halo effect is when one good quality makes us think everything about a person or thing is good. If someone is friendly and well-dressed, we might assume they're also smart and trustworthy, even without evidence.