Good and bad

The words "good" and "bad" are a basic way of talking about value or ethics. They are often used in different ways to talk about things, people, ideas, or actions as being either good or bad. Many questions about the concepts of "good" and "bad" are studied by philosophers. There are many different beliefs about what is good or bad, or about what the two words really mean. These differences can often be seen in different cultures and religions.
Good "for something" and good "in itself".
In philosophy, goodness is generally understood in two main kinds: either a thing is good or it is good . For example, eating properly may be good (provable) but eating properly may not be a good (unprovable). This also applies to things that are called bad. The belief that there are such things as good and bad has been a main part of Western philosophy since Plato. However, some philosophers have rejected this belief.
A relative good is something that is good because people say it is good. An absolute good is something that is good because of something in itself. It is good even if there is no one around to see it. For example, an economist may say that the Mona Lisa is a very valuable economic good because it can be sold for a lot of money. A philosopher may say that the painting is good because of how it is painted. The economist sees relative good, because people may later not want to pay for it. The philosopher sees absolute good, because it will always be painted well.
Good and evil.
Good and evil are opposites. 
And people have opinions on what things are good and what things are evil. For example someone might think killing someone is evil and another person thinks it's good (it is evil! Do not do it!).