Weight:Weight is the force exerted on an object due to gravity. It depends on both the mass of the object and the acceleration due to gravity.
Inertia:Inertia is the tendency of an object to resist changes in its state of motion. Objects with greater mass have greater inertia.
Density: Density is a measure of how much mass is contained within a given volume. It can be calculated by dividing an object's mass by its volume.