Definition of nuclear fission

How is it nuclear fission used?

What fuel is usually used in nuclear fission?

Info on nuclear reactor fission:

What are the safety issues regarding nuclear fission?

Explain how chain reactions happen in nuclear fission

Definition of nuclear fusion

Conditions needed for nuclear fusion?

How much energy does nuclear fusion create?

Why can't nuclear fusion be used yet for generating electricity?

Where does nuclear fusion happen in nature?