Chocolate is made from the roasted seeds of the cacao tree. The seeds are bitter, and fermentation develops their flavour. Later the seeds are dried, cleaned, roasted, de-shelled, and ground into liquefied form (chocolate liquor). There are six flavours:

• Unsweetened (bitter) chocolate contains cocoa solids and cocoa butter
• Bittersweet chocolate is chocolate liquor mixed with sugar, cocoa butter, vanilla, and sometimes lecithin
• Semi-sweet chocolate is a dark chocolate with a low sugar content
• Dark chocolate is made of cocoa solids mixed with fat and sugar
• Milk chocolate contains cocoa solids mixed with powdered milk or condensed milk
• White chocolate does not contain cocoa solids, but is a mixture of cocoa butter, sugar, and milk

Grocery stores sell packages which usually contain 8 squares of brown chocolate, and 6 squares of white chocolate. Each square = 1 oz.

Those are okay, but chocolate shoppes and farmers markets generally sell higher quality blocks of chocolate, which have a better flavour. I prefer Callebaut.

Brands like Nestle or Hershey are suitable for s’mores, but they contain oils to extend their shelf life. This affects  melting temperature and how they bond with other ingredients, so I avoid them for baked goods. You’ll find the same issue with chocolate chips; they are fine in cookies but also contain additives so I wouldn’t use them in anything fancy.