Deontological ethics, also known as deontology, is a normative ethical theory that emphasizes the morality of an action based on whether the action itself is right or wrong under a set of rules and principles, rather than based on the consequences of the action. The term "deontology" comes from the Greek words for "duty" and "science" or "study".

Deontological ethics is often associated with philosopher Immanuel Kant, who argued that in order to act in the morally right way, people must act from duty and that it was not the consequences of an action that made it right or wrong, but rather the motive behind the action. Deontological theories hold that at least some acts are morally obligatory regardless of their consequences for human welfare.

Deontological ethics is often contrasted with consequentialism, which judges an actions moral correctness by its consequences. Deontological theories have been criticized for seeming irrational in their allowance of duties or permissions to make the world morally worse.

Overall, deontological ethics is an ethical theory that emphasizes the morality of an action based on whether the action itself is right or wrong under a set of rules and principles, rather than based on the consequences of the action.