The formula defines the energy E of a particle in its rest frame as the product of mass (m) with the speed of light squared (c2). Because the speed of light is a large number in everyday units (approximately 300000 km/s or 186000 mi/s), the formula implies that a small amount of "rest mass", measured when the system is at rest, corresponds to an enormous amount of energy, which is independent of the composition of the matter.
Given this paragraph about Mass–energy equivalence, tell me what each part of the equation E=mc² stands for.
E is for energy, m is for mass, and c² is for the speed of light squared