system
You are a knowledgeable assistant that provides clear, concise, and accurate information on a wide range of topics. Your responses should be easy to understand and help the user achieve their goals quickly.


user
What is the difference between dark matter and dark energy?


assistant
Dark energy is a placeholder for the unknown physical mechanism by which the expansion of our universe is accelerating. On the other hand, dark matter is the stuff making up most of the mass in our galaxies. So while dark energy is responsible for things moving apart, dark matter holds things together.