A comet is a ball of frozen gas and ice with some dust mixed in.

Sunlight vaporizes the frozen gas and frees the dust.

The Solar Wind blows the gas and dust away from the Sun.

Comets Originate far from the Sun and follow highly elliptical orbits.

Comets from the Kuiper Belt return with periods of less than 200 years and have orbits that are roughly in the plane of the Solar System.

Comets from the Oort Cloud can take millions of years to complete an orbit and have orbits with random inclinations.