What is a good abstract?

In this article I will discuss abstracts for scientific papers and articles on art and technology.

There are probably many people better qualified to write this post than me, but as a regular reviewer for journals, conferences, grant applications, books etc. I guess it really matters to some people what I am looking for in an abstract, even if I am only one of many reviewers, even if my opinions are unconventional (for instance in the arts). So, what do I think are the properties of a good abstract?

I think a good abstract is (i) informative, (ii) clear and (iii) succinct. Obviously these aren't mutually exclusive properties, they are closely related. To be informative, tell me what I need to know. More on that in a second. To be clear, avoid jargon and keep terminology simple. Avoid references to other material (keep that for the introduction/background). The abstract is not post-modern poetry. Please explain yourself as simply and clearly as you can to engage as many people as possible. If you want people to read your paper, you must be understood by them from the beginning. To be succinct provide an overview but no detail, don't waffle.

What is needed for an abstract to be informative? Tell me directly what you have done. Tell me why you did it and convince me that it is important. Then tell me how you did it - briefly! This is the abstract, not the method/approach so keep it short. If the technique you used is well-known just name the technique. If the technique is related to a well-known technique, just name the technique and say that you used a custom or previously published variant of it. Lastly, tell me your conclusions, but just the main findings. This isn't a mystery novel. The reader mustn't be kept guessing until the Results section. Please include this information upfront.

That's it. I hope that isn't too much to ask. I must remember these guidelines myself next time I write an abstract.