Dihydroergotamine is used to treat migraine headaches and cluster headaches. It is not recommended for migraines that affect only one side of the brain (hemiplegic migraine) or the base of the brain /neck area (basilar migraine), or to prevent migraines from occurring.
Pop music is an abbreviation for popular music. In other words, the main difference between pop music and alternative or underground music is the kind of following it has: pop music is usually known by a lot of people and regularly appears on TV.
Answer Wiki. In the pop world the most famous music is often the best since pop is measured very largely by popularity. In the classical world that is not necessarily the case. The best-selling classical pieces are those that have been used in some non-classical context e.g. as film music, TV commercials or modernised into some popular song.