Lawyer-client conversations are private, so clients can share personal details without worrying that it will get out. This is called legal professional privilege and it helps clients be open with their lawyer, so they can get the best advice. It builds trust and ensures the lawyer fully understands the case. There are some very rare exceptions (such as if the client says they are about to injure another person or the client chooses to make the information public) but for the most part, its confidential.