* Mass of either object changes: The more massive an object, the stronger its gravitational pull. So if either object gains or loses mass, the force changes proportionally.

* Distance between the objects changes: Gravity weakens rapidly with distance. The force of gravity between two objects decreases by the square of the distance between their centers. So, if the objects move closer, the force increases, and if they move farther apart, the force decreases.

In summary, the gravitational force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

Here are some examples:

* The Earth's gravity: As you climb a mountain, you move further from the Earth's center, so the gravitational force on you slightly decreases.

* The Sun and the Earth: The Earth's orbit isn't perfectly circular, it's slightly elliptical. When the Earth is closer to the Sun, the gravitational force is stronger, and when it's further away, the force is weaker.

* Black holes: Black holes have immense mass concentrated in a tiny volume, leading to extremely strong gravitational forces.

It's important to note that while the force of gravity changes with mass and distance, it never truly disappears. It just becomes incredibly weak at very large distances.