The term is most widely used  as an analytical convenience to denote a portion of a movement identified as an example of classical tonal sonata form . The exposition typically establishes the music's tonic key , and then modulates to, and ends in, the dominant .  If the exposition starts in a minor key, it typically modulates to the relative major key, or less commonly, the minor dominant. There are many exceptions—for example the exposition of the first movement of Beethoven's Waldstein Sonata modulates from C major to the mediant E major. The exposition may include identifiable musical themes (whether melodic , rhythmic or chordal in character), and may develop them, but it is usually the key relationships and the sense of "arrival" at the dominant that is used by analysts in identifying the exposition. The exposition in classical symphonies is typically repeated, although there are many examples where the composer does not specify such a repeat.
In spite of the above, once everything I’ve said has been taken into account, it is still true that people should devote a great deal of their resources to famine relief and similar causes—in all likelihood far more than most people in affluent nations, including me, either do contribute or want to contribute. I would thus say that Singer’s main argument is sound, provided we accept the weaker version of Singer’s second principle, ., that one should prevent morally bad states of affairs if one can do so without sacrificing something morally significant. It’s just that I happen to think that having the moral autonomy to pursue one’s interests is something morally significant, and from the foregoing it should be clear that this means one is morally free not to devote oneself to working full time to prevent famine. However, I would question the stronger version of the second principle, ., that one should prevent morally bad states of affairs if one can do so without sacrificing something of roughly equal moral importance to the bad states of affairs one is trying to prevent. I question it not because I think it is false , but because I think in many cases it is vague whether two or more states of affairs are of roughly equal moral importance. In the case I considered earlier, there was a tradeoff between choosing to do something, namely donating to famine relief, which has a high probability of producing very beneficial results, and choosing to do something else, namely pursuing one’s interest in such things as higher mathematics, which has a much lower but still non-negligible probability of producing very beneficial results. The problem is that it is by no means obvious how we can compare the “beneficiality” of these results when we simply don’t know what results pursuing one’s interests might have, nor how beneficial they might turn out to be. For these reasons I think that while Singer’s conclusions are correct, they aren’t quite as correct as he thinks they are.
The fiction books, articles and magazines that people read in their everyday lives essentially rely on exposition to connect the readers to the main story by giving them the background information. In most cases, a narrative or script loses its essence if not accompanied by an exposition. Not only is it important for bringing clarity to a script but it is also vital to enhance its literary value. The true essence of a book usually lies in how the reader is introduced to the characters in it and, if done correctly, the reader automatically starts relating to them.