Ethics is the study of good and bad behaviour. It is one of the main parts of philosophy. Ethics tries to answer questions like:

 What actions are good? What actions are evil?
 How can we tell the difference?
 Are good and evil the same?
 How should we make hard decisions that might help or hurt other people?
 How do our actions affect others?

Ideas about ethics 
When discussing ethics, the philosophy is generally separated into:
 thinking about morality,
 the involvement of science, 
 the freedom of people to decide for themselves how to act within their own beliefs.

Morality is what someone thinks or feels is good or bad.
There are many different moralities, but they share some things.
For example, most people think that murder (killing somebody) is wrong.(compare Exodus 20:13)
Some philosophers have hope to find more things that moralities share.
They think that ethics should use the scientific method to study 
things that people think are good or bad. Their work can be used
to test the fairness of a situation, such as how people should treat
each other. An example of this kind of thinking is the categorical imperative.
Many countries have laws based on this idea of fairness.

What is ethics used for? 
Understanding ethics can help people decide what to do when they have choices. Many philosophers think that doing anything or making any choice is a part of ethics.

Ethics is part of other fields of study in many ways. Here are some ways:

 Ethics is part of the study of religion. In religion, people often learn what is good or bad from what they believe about God (or gods). Some important ideas about what is good or bad have come from religion. See Ten Commandments.
 Some theories of economics say ethics has to do with money. Money is a big part of most people's lives. Thinking about morality can be important in economics. For example, there is a saying about ethics taken from the Bible that 'the love of money is the root of all kinds of evil' (1 Timothy).The philosophy of Marxism also says that a few people using money in the wrong way can hurt many other people.
 Government policy can be affected by what politicians think is ethical. Politicians try to create laws that help everyone do what is right. Political debates happen when the people who make public policy do not agree about what is right.
 In work, thinking about ethics can help with hard questions. Work can be like both economics and politics. Workers have to make money and follow laws. But the best way to do both is not always easy to know. The study of this is called business ethics
 People like doctors and nurses have to make hard choices about how to care for people. Sometimes the person being cared for, their family or the doctor do not agree what is best for them. Also, choices have to be made if there are enough resources to help all. The study of this is called medical ethics. Similar studies for specific professions include bioethics and legal ethics.
 Discussing ethics can also be a way to stop people fighting or starting a war. By talking about ethics, people hope to get what they want without being violent. This works when all people agree that peace is very important. But not everyone agrees about what is right or wrong. So, sometimes anger can make it hard to talk without fighting.

Along with aesthetics ethics forms part of axiology, the philosophy of what people like.

Related pages
 Conflict of interest
 Ethical tradition
 Morality
 Utilitarianism
 Virtue
 The Republic, a book by Plato that says that people who have power should use ethics to make choices.
 The Prince, a book by Niccolò Machiavelli that says that people who have power should not use ethics to make choices.

Further reading
 Aristotle, Nicomachean Ethics
 The London Philosophy Study Guide  offers many suggestions on what to read, depending on the student's familiarity with the subject:  Ethics 
 Encyclopedia of Ethics. Lawrence C. Becker and Charlotte B. Becker, editors. Second edition in three volumes. New York: Routledge, 2002. A scholarly encyclopedia with over 500 signed, peer-reviewed articles, mostly on topics and figures of, or of special interest in, Western philosophy.
 Blackburn, S. (2001). Being good: A short introduction to ethics. Oxford: Oxford University Press.
 De Finance, Joseph, An Ethical Inquiry, Rome, Editrice Pontificia Università Gregoriana, 1991.
 Derrida, J. 1995, The Gift of Death, translated by David Wills, University of Chicago Press, Chicago.
 Fagothey, Austin, Right and Reason, Tan Books & Publishers, Rockford, Illinois, 2000.
 Solomon, R.C. Morality and the Good Life: An Introduction to Ethics Through Classical Sources, New York: McGraw-Hill Book Company, 1984.
 Vendemiati, Aldo, In the First Person, An Outline of General Ethics, Rome, Urbaniana University Press, 2004.
 John Newton, Ph.D. Complete Conduct Principles for the 21st Century, 2000. .
 Guy Cools & Pascal Gielen, The Ethics of Art. Valiz: Amsterdam, 2014.
 Lafollette, Hugh [ed.]: Ethics in Practice: An Anthology. Wiley Blackwell, 4th edition, Oxford 2014.

Other websites
 Brute Ethics: animal ethics encyclopedia