QUOTE : If you know why you have chosen to work on a particular problem, it is easy to present an absorbing seminar. Start out by telling your story, why the field you are working in is an important one, and what the main problems are. Give some historical material showing where the field is, the relative advantages of different methods, and so on. Then outline what you did, and describe your results. Conclude with a statement of how your results have advanced our understanding of nature, and perhaps give an inkling of the new directions that your work opens up. Do not assume that your audience comprises experts only. There may be a couple of them, but even experts like to hear things that they understand and particularly to have their colleagues hear (from someone else) why their field is an important one.