The speed of light is a universal physical constant. It is equal to 299792458 meters per second (approximately 300000 km/s). We use the letter “c” to denote it. Yes, it is the “c” in E=mc^2. This constant has a crucial role in analyzing space travel. Also, the universe’s expansion is understood to exceed the speed of light beyond a certain boundary.
The fundamental constant of physics, the Boltzmann constant, is one of the seven "defining constants" that have been given exact definitions.