What could life be if you know nothing about the weight of a particular something? How can you measure grain and sell it with a constant price? How can you tell if you are overweight, underweight or normal? How can laboratory technicians weigh what is enough for specific ingredients? How can a driver know if the vehicle driven can pass through a particular bridge without giving it a crack and fall? How can vegetables and meat produce be sold? Some weights need exact measurement like those in the lab. Some need only approximation, still, knowing the weight is important in our everyday lives that a weighing balance is everywhere.