ELI5 Chocolate - milk, dark & white, what's the difference?

Why do Oreos get soggy in regular milk but not in chocolate milk? What is the difference between dark chocolate, milk chocolate and white chocolate? What is the % number I see on chocolate packaging and labels?   ... We explain like i'm five!   Thank you to the r/explainlikeimfive community as always and in particular the following users whose questions and comments formed the basis of this discussion: eliteanaconda57, thielio, rtap15, irythros, krystar78, xerloq, barefootess, clevalandfansadface & thejayhook To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter: https://www.twitter.com/eli5ThePodcast/ or send us an e-mail: [email protected]