What element used in gun powder?

In Black Powder, the oldest type, the element sulfur is a key ingredient. The compound sodium or potassium nitrate is also used, as is charcoal. For a reason not fully understood, the element carbon cannot be substituted for charcoal- which is basically carbon.

SMOKELESS gunpowder, used in modern ammunition, is typically made of complex compounds, such as nitroglycerin and/or nitrocellulose, and not elements.