A balance scale is a device used to measure the weight or mass of an object. It is commonly used to compare the weights of objects or to weigh objects by balancing them with standard weights. The key difference between a balance and a scale is what they measure: balances measure mass, while scales measure weight. Mass is the amount of matter in an object, while weight is the force exerted on an object due to gravity. A true balance measures mass directly by comparing the unknown mass to a known mass, a process that is not affected by changes in gravity. On the other hand, a scale displays weight by measuring a deflection, and the force needed to deform the springs is measured and converted into weight. There are several types of balance scales, including beam scales, spring scales, and digital scales.