is the speed of light the fastest of all speeds

In a vacuum, the speed of light is the fastest possible speed. It's approximately 299,792 kilometers per second (km/s) or about 186,282 miles per second (mi/s). This speed is a fundamental constant of nature and is denoted by the symbol "c."

The speed of light is the universal speed limit in Einstein's theory of relativity. No particle with mass can reach or exceed it, as the energy needed to accelerate to that speed would be infinite. Light itself, being massless, travels at this speed.

However, in other media such as water, glass, or air, the speed of light is slower than in a vacuum due to interactions with the material's particles. But for any given medium, the speed of light still remains the fastest speed at which information or objects can travel.