Orbits

An orbit is essentially the circular path an object takes around another object due to gravity. This is a general definition of orbits but it becomes much more useful when applied to satellites in low-earth orbit or planets around the Sun. However, the orbits of planets around a star are usually more elliptical than satellites so if you want to analyze those orbits, go a little further below.

In an orbit, gravity is usually providing the centripetal force required for the object to stay in orbit. This is universally true for any object orbiting a more massive object. Orbits can theoretically be indefinite but due to effects like gravitational radiation and solar winds, this won't be the case, even for orbits like our Moon around Earth and our Earth around the Sun.