We see an object when light travels from the object to the eye. Optic nerves carry information about the object from the eye to the brain. The brain processes the information.
Light travels from the object to the eye when the object is emitting or reflecting light. Another way to put it is, we can see luminous (emitting) or illuminated (reflecting) objects.
A star, a light bulb, a burning log, and a toaster all emit light.