Optic means relating to the eye or vision. Your optic nerve carries visual information from your eye to your brain, like a cable transmitting images from a camera to a screen. Without your optic nerves working properly, you couldn't see anything, even if your eyes themselves were perfectly healthy.

The word appears most often in scientific and medical contexts. An optician makes and fits eyeglasses, while an ophthalmologist is a doctor who treats eye diseases. Fiber optic cables use light to transmit information at incredible speeds, sending data through thin glass strands the way your optic nerve sends signals through nerve fibers.

Sometimes people use optics to mean how something appears or looks to others. When a politician says she's concerned about the “optics” of a decision, she means how it will look to voters, whether it will seem good or bad. This usage comes from the idea of visual appearance: the “optics” of a situation are what people see when they look at it.