It is a matter of common knowledge that chocolate is made from cocoa. In fact for most people chocolate and cocoa are synonymous. Chocolate is made from the fruit of the cacao tree. This tree is a native of South America. The ancient South Americans found it more useful to use the cocoa seeds as a sort of currency than use it for making chocolate.
So, how do you get chocolate from the cocoa seeds? The cocoa beans undergo a lot of processing before they are in the form that we recognize as chocolate. Firstly they are fermented. Next, they are sun dried and bagged before being exported. To develop the distinctive flavor of chocolate, the cocoa beans are sorted, cleaned and roasted. These roasted beans are then shelled and grounded. The intense heat of the grinding process melts the fat in the cocoa beans resulting in a fatty material with a bitter taste called the chocolate liquor. From this liquor cocoa butter or yellow fat is separated leaving behind a solid cake. This is then ground and sifted to manufacture cocoa powder.
To make the chocolate that you get in the market, sugar, additional fat and milk and other things depending on the type of chocolate that is required, is added to the chocolate liquor. The fat that is usually added to the chocolate is cocoa butter which gives it the melting sensation. Most countries including US permit only this fat to be added to the chocolate but some countries also permit the addition of vegetable fat.