Why did Marley have chains in his body and what is the meaning of the chains in Marley's body?

Marley is chained up because the chains represent all the wrongs and sins in his life, he tell scrooge that his chain will be far longer than his because he is still alive and still doing wrong. marley is never allowed to rest and has to keep moving around the world dragging his chains with him as punishment for the wrongs he did in life.

Hope this helps! :)