Dark chocolate, also called “plain chocolate” or “black chocolate”, is produced by adding fat and sugar to cacao. It is chocolate with no milk, or with much less milk than milk chocolate. The US has no official definition for dark chocolate, only “sweet chocolate”, which requires a 15% concentration of chocolate liquor. European rules specify a minimum of 35% cocoa solids. Dark chocolate may be eaten as it is, or used in cooking. Bars with up to 85%, or sometimes 99%, cocoa are sold. Chocolate with higher cocoa percentages is more expensive.