An orbit is the curved trajectory of one object around another.
An orbit is the curved trajectory of one object in space in relation to another object. There are different kinds of orbits. Some are closed, such as circles or ellipses. Others are open trajectories such as parabolic and hyperbolic paths. The Moon orbiting the Earth, and Earth, or other planets, orbiting the Sun, are examples for near-circular and elliptical orbits. Comets and asteroids typically have highly elliptical orbits. One-time visits by objects from beyond the Solar System will be on parabolic or hyperbolic orbits. Kepler's laws of planetary motion describe all these orbits.
An orbital plane is the flat, disk-shaped space that connects the center of the object being orbited with the center of the orbiting objects. Because all planets in our solar system share a similar orbital plane, planets don't run into each other. Graphic Credit: Tim Gunther, National Geographic
Planets, comets and asteroids in our solar system orbit the Sun with closed elliptical orbits. Objects that come from outside the Solar System have open hyperbolic paths. They are moving too fast for the Sun to capture them, so they’ll eventually escape back into interstellar space. Credit: Roen Kelly, Astronomy Magazine