Consists of two types, semisweet (used for cooking) and bittersweet (more cocoa, vanilla). However, both can be referred as 'couverture', that is chocolate rich in cocoa butter
It has more antioxidants than milk or white chocolate. However, avoid anything with caramel, nougat or other fillings. These fillings are just adding sugar and fat which erase many of the benefits you get from eating the chocolate.
Susan: You mean African American male?
Mary: No, the one that melts in your mouth.... you've read Urban Dictionary too much