* 299,792,458 meters per second (m/s)

* 186,282 miles per second (mi/s)

This is a fundamental constant in physics and is represented by the letter c.

Here's why:

* Photons are massless: Photons have no mass, which is why they can travel at the speed of light.

* Special Relativity: Einstein's theory of special relativity states that nothing with mass can travel at the speed of light. Since photons are massless, this restriction doesn't apply to them.

It's important to note that photons always travel at the speed of light in a vacuum. Their speed can be slightly slower when they are traveling through a medium like water or glass.