Answer :

When we mean weight in general, we are implying the amount of human body material that we possess in us.  That is 50 Kg etc..  But in physics weight means the force of gravity that the earth is exerting on a body, that possesses mass.

Any body or object that occupies space has a mass (amount of matter). This object is attracted towards the earth's center by a force called gravitational force.  That is why an apple thrown high in to the sky returns back to the surface of earth. If possible it will travel to the center of Earth deep inside.

This force of attraction by the gravitational principles is called the weight.  It is equal to mass multiplied with g = 9.81m/sec. on the surface of earth.  A person with a mass 50 Kg is actually 490.5 Newtons  heavy.  This force is felt by us at the bottom of our feet.

When a Lift (elevator) goes up, we feel heavier or lighter during brief moments.  This is because the Lift exerts some force in the upward direction or downward direction. That adds to or reduces the effect of gravity. 
More pronounced is the weightlessness or heaviness experienced when one goes on a giant wheel, roller coaster, water slide ...

So weight is a force.  All the persons inside a satellite in distant space feel weightless. All the objects, floor, ceiling, tables, astronauts are moving at the same speed in the same direction in space around the Earth. So one person does not feel heavy under the feet on the floor. Truely speaking they have weight, but they do not feel it.

Weight is a force that depends on the mass (50 gms or 50 kgs or pounds) and the attraction of the planet on which we reside.  If we go on to the Moon, the attraction we experience from the moon is only 1/6th of that on Earth. So we fell very light and our weight becomes 1/6th only.  A high jumper may be able to jump over a bar placed at 6 times higher than on earth, if he gets the same lift he does on earth by pushing the ground with his/her feet.

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