what is the background of Oliver and which kinds of problem he had to face in London?

Oliver is a young, good-hearted, and kind--but often mistreated--orphan who is raised in a workhouse, and finds himself indentured to an undertaker, living with thieves, and eventually taken in by the kind Mr. Brownlow and Mrs. Maylie. His generosity of spirit is total, and even when faced with serious maltreatment, he never loses his sense of morality or kindness.