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.
What is pop music? The definition of pop music is deliberately flexible as the music that is identified as pop is constantly changing. At any particular point in time, it may be easiest to identify pop music as that which is successful on the pop music charts.