Why do we study comets? NASA explains (NASA)

There are so many of them and the spectacular comet list includes Halley's Comet, Comet Hale–Bopp, 81P/Wild, 67P/Churyumov–Gerasimenko, Comet Encke, Tempel 1, 19P/Borrelly, Comet Shoemaker–Levy 9, 55P/Tempel–Tuttle and many more. (NASA)

Comets are mostly named after their discoverer, says NASA. This can either be a person or a spacecraft. If a spacecraft discovers them, then they may have LINEAR, SOHO or WISE in their names. (NASA)

Why do we study comets? NASA says to better understand how long ago the solar system began and evolved to what it is today. Yes, comets help in doing so. (NASA)

NASA has sent several spacecraft to visit comets. Deep space 1 flew by comet Borrelly. The Stardust spacecraft collected dust from the coma of comet wild 2 and returned the samples to earth.  (NASA)

The Deep impact spacecraft sent a smaller impact craft directly into the path of comet Tempel 1 to learn more about the inside of a comet nucleus (the solid part). (Reuters)

In fact, in 2011 Stardust-NExT returned to Comet Tempel 1 to see how the surface has changed after the comet completed one full orbit around the Sun. (Reuters)