What is a modulation,and how to use it.

                                                                                                                                                                    A modulation (a key change within the song) can provide a song’s most dramatic and memorable moment. Although there are no rules relating to this (or anything else in songwriting), most often, the modulation occurs at the beginning of a song’s final chorus and raises the key either a half or a whole step. Notable examples include the chill-inducing final choruses in Whitney Houston’s version of Dolly Parton’s “I Will Always Love You”                       There are quite a few ways to use lyric twists and melodic surprises to separate your songs and engage your listeners. While it is unlikely that you will want to incorporate the technique in all your songs, by thinking about—and trying on—some of the tools, you might be surprised at how you can twist your song into a hit.