An orbit is the path of one body round a larger one, held in place by gravity. Moons orbit planets. Planets orbit the Sun in paths that are nearly circular. Artificial satellites, which are man-made, usually orbit the Earth.
Comets are different. A comet moves on a very elliptical orbit, a long stretched oval, with the Sun off-centre. A comet speeds up as it falls towards the Sun and moves fastest when it is closest to it. It moves slowest when it is furthest away, and may take many years to return.
Artificial satellites have useful orbits. A satellite in low orbit takes about 90 minutes to go once round the Earth. A geostationary satellite orbits above the equator, takes 24 hours, and moves in the same direction as the Earth spins, so it stays above one point on the surface.
