Do you mean literally the world as a planet?
If so, inertia. Make something move in space and it won't stop until something else stops it. Things stop moving "alone" down here on Earth because of friction (from the ground, from the air). In space it doesn't happen.
If you mean what makes 'our' world go round, as in what moves society and cultures, well that's a lot more subjective. Some people will say money, some will say science, love, compassion, greed, selfishness, technology, curiosity, exploring, etc.