Why helloooo, clareise... jk whats up?

On heads, cams, and intakes, but especially cams, when they mention a rpm range is that the range that particullar part makes power? or is that the true limits of that one part? Example if one had a cam of 900-4800 rpm range and they took the engine up to 5500 rpm would they grenade the engine?

Thanks,

-Chris.