Bullion is just the term for precious metals sold in bulk. Investors can purchase bullion in rounds or bars. Bullion gets its value from its weight and the current spot price of the metal. Becuase of this, the value of bullion investments fluctuates daily, depending on global market values of gold, silver, copper etc. While you can invest in bars, the most popular coins are the Canadian Maple Leaf, the South African Krugerrand, and the American Gold Eagle.