Gravity is the force the attracts an object to a larger physical body that has more mass. This force is not just on Earth, it acts everywhere in the universe. Two factors that affects the gravitational force is the mass of the objects and the distance between the two or more objects. The more mass an object has, the more gravity it has, less mass means less gravity. Also, if you are further away from an object, the gravitational force gets weaker and that is why astronauts can float in space.
Gravity is what keeps everything on Earth. Without it, we would all be flying around dead.
The more mass an object has, the more it alters the whole plane of space and time.
The weight of an object shows how much gravitational force is acting on it. This is why people weigh differently on different planets, they have a weaker or stronger gravitational pull. People usually confuse weight and mass, mass is how much matter you have, and weight is how much gravitational force is acting on you.
What does weight have to do with gravity?
Both weight and gravity are forces, meaning they are connected. Weight is a gravitational force, the weight of an object shows how strong the gravitational force between the object and other object, like a planet, is. The greater the mass of the object, the greater the gravity acting on it, resulting in the object weighing more. Without gravity, there is no weight, you would not weigh anything and could fly, and so could everything else, like animals, cars, and other objects that aren't connected to the Earth. Weight and gravity co-exist with each other and are needed for each other, even though there can be gravity without weight.