Gravity holds us to the surface of the Earth and keeps our atmosphere wrapped around our planet. An object’s weight is a measure of the gravitational force acting on it.
If you visited another world, you would notice a change in your weight, because the force of gravity acting on you there would be different from the force of gravity here on Earth.
Gravity exerts a force of attraction between any two objects—the Earth and you, for example. Its strength depends on the amount of mass (matter) each one has and on how far apart their centers are. The more mass something has, the more gravity it has. The farther apart two objects are, the weaker the force between them becomes. So, if you visited another world, your weight would change because the mass and size of that world would differ from Earth’s, which means that the force of gravity acting on you would be different too. Your mass, however, would not change.