What kind of ammunition was used in muskets?

Muskets were muzzle loading firearms- MOST with smooth bores. They used gunpowder poured own the barrel, and a lead ball that was pushed down the barrel with a ramrod. RIFLED muskets might use a round lead ball wrapped in a greased cloth patch, or a lead Minie Ball- but still required powder to be poured down the barrel. The powder was sometimes wrapped in thin paper tubes (cartridges) that could be bitten open, and powder dumped down the barrel. Check Wikipedia for the term Minie Ball for more information.