To understand the different types of chocolate its important to understand how chocolate is made and what it actually is.
Chocolate is made from the cocoa beans which are dried, roasted and ground. The grinding process produces a thick dark paste known as cocoa solids or cocoa mass. The cocoa solids are the basis for all chocolate and cocoa products. Further processing of the cocoa mass extracts a naturally occurring cocoa butter, which gives chocolate its high gloss appearance, smooth texture and melting properties.
There must be at least 20% of cocoa butter for products to be called REAL chocolate.
Chocolate does not like excessive heat or little drops of water. When melting chocolate great care must be taken. If chocolate is heated too high it begins to cook resulting in a dull thick paste. Around 30-35°C is ideal. Milk and white chocolate are even more vulnerable.
If a drop of water mixes with the chocolate when melting it causes the chocolate to seize up, resulting in a solid grainy mass that cannot be remelted or used.