Is a duplicate, a duplicate question or a duplicate answer?

Question

Because of a recent question I've been wondering what duplicate actually means.

Researching the issue here and on meta.SE has not given me a conclusive answer but I did notice my own thoughts reflected a few times.
I've also noticed some cases of people disagreeing with what a duplicate is.

So I'm wondering if we can put a definite answer to:

1. Are duplicates duplicate questions
2. Are duplicates duplicate answers
3. When do we close as duplicate

I'm of the idea that there probably isn't some line in the sand that determines a duplicate. But there should be a clear idea of when something is a duplicate, and when something is a unique and connected issue.

Answer 1

Are duplicates duplicate questions

Are duplicates duplicate answers

The text that is inserted into the question when it is closed as a duplicate gives a clue as to it's intended usage

Something that reinforces this is that you cannot close a question as duplicate if the target has no answers. Duplicates are questions that already have an answer.

When do we close as duplicate

Close as duplicate when the answer to the question is answered by the target - simples.

Allegedly one of the greatest benefits of the SE engine is that questions that already have answers can be closed a duplicates. Sadly it's often way easier to answer a question that you know already has an answer than it is to find the duplicate you know exists.

Answer 2

A duplicate is when the question you're posing, is answered in another thread.

If you have a problem which is clearly solve-able by the answer provided to someone else's question. Even if that question is not the same as yours. Your question is a duplicate of theirs.

This in no way invalidates your question.
It's very hard to look for a duplicate as someone asking a question, if the other question does not resemble yours.
And you are in no way at fault for not finding the duplicate.

The main purpose of this site is the collection of knowledge.
If your question has an answer that is already properly explained, stating it again is just noise.
And having several similar posts makes updating them when they're outdated increasingly difficult.

Don't look at closing your question as a duplicate as a bad thing.
We're simply pointing you to your answer, and nobody is disputing that you probably have a valid question.
It's simply been answered before, and that's great!
We've just saved a lot of time and effort and at the same time resolved your issue!