ELI5 Blood - how does circulation work after an amputation?

Why does blood not stick to human skin like a permanent marker, yet stains things like clothes really badly? How does circulation work after an amputation? How many blood types are there? What does A B & O mean? If blood in your veins looks blue, why do we never see blue blood when we get a cut?   ... 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: liquidbottle, old_story, uniwersal, turbotitan92, despicablenewb, alloftheabove12, kyylye, somepoet, skillyskally & phage0070 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]