Final answer:
Light is electromagnetic radiation that can travel through empty space and various media, reflecting and refracting as necessary. Visible light is a small fraction of the electromagnetic spectrum, which moves at a constant speed in a vacuum.
Step-by-step explanation:
Light is a kind of electromagnetic radiation and can therefore travel through matter and space. As electromagnetic radiation, light exhibits wavelike behavior as it moves through space and does not require a medium like sound does. This means that light can travel through a vacuum, like the space between the Earth and the Sun, as well as through various media such as air and glass. Visible light is only a small part of the electromagnetic spectrum, which also includes gamma rays, x-rays, and radio waves, to name a few. All forms of electromagnetic radiation move at a constant speed in a vacuum, approximately 3.00 × 10⁸ m/s. Light may also be reflected from a mirror or change direction when it transitions from one material to another, in which case it continues to move in straight lines known as rays.