Exoplanets are planets that orbit stars outside of our own Solar System. The discovery and study of these distant worlds have revolutionized our understanding of planetary formation and the potential for life beyond Earth.
Some of the most scientifically important astronomical objects are the ones that push the boundaries of definitions. These objects can exist in the grey areas between competing definitions. They motivate astronomers to develop a deeper and more comprehensive understanding of Nature. One of these important dividing lines places planets on one side and stars on the other.

