When you jump up, a force will make you fall down again. This force is known as Earth's gravity, which is an attractive force between you and the planet. 

Earth's gravity can be measured with a spring scale, and its unit of measurement is a newton (N). A spring scale shows how strong the attractive force between the weight and the Earth is. The resulting measurement determines the object's weight.

Balance scales are used to measure mass. The unit of mass is the gram (g) or the kilogram (kg), which is a thousand grams. 

The difference between mass and weight is that the mass of objects is constant, no matter whether you are on Earth or on the Moon. In contrast, the weight of an object can vary depending on the gravity that affects it. The attractive force between an astronaut and the Moon is smaller than that of the same person and the Earth. This is why people weigh less when they are on the Moon than they do when they are on Earth.