Which of these is sometimes described as duty, obligation or rule-based ethics?

In moral philosophy, deontological ethics or deontology (from Greek δέον, deon, "obligation, duty") is the normative ethical theory that the morality of an action should be based on whether that action itself is right or wrong under a series of rules, rather than based on the consequences of the action. It is sometimes described as duty-, obligation- or rule-based ethics. Deontological ethics is commonly contrasted to consequentialism, virtue ethics, and pragmatic ethics. In this terminology, action is more important than the consequences.

The term deontological was first used to describe the current, specialised definition by C. D. Broad in his 1930 book, 'Five Types of Ethical Theory'. Older usage of the term goes back to Jeremy Bentham, who coined it before 1816 as a synonym of Dicastic or Censorial Ethics. The more general sense of the word is retained in French, especially in the term code de déontologie (ethical code), in the context of professional ethics.

Depending on the system of deontological ethics under consideration, a moral obligation may arise from an external or internal source, such as a set of rules inherent to the universe (ethical naturalism), religious law, or a set of personal or cultural values (any of which may be in conflict with personal desires).