Modes are ancient scales of the church which are still used today by jazz musicians. You can also hear modal music in many of today's film scores and in some churches who still value their rich musical heritage. Film composer John Williams composes many of his movie themes in modes. One of the first jazz musicians to come to mind when I think of modes is Chick Corea. Most jazz musicians are actually drawn to these classical scales because they are very rich in melodic and harmonic possibilities. The church, in an effort to dumb down for the common person is actually dumbing down the common person. If you can find a church offering a Tridentine Mass, most likely you will hear a lot of modal music. As much as I love contemporary Christian music, it is very much trapped in the Ionian Mode (major scale) and doesn't give a sense of the sacred as many other modes do. When I attend other churches, I usually leave feeling numb from the "white bread" music and musicians.
This video is a simple example of how one may explore the modes as an improvisational tool. One does not need to explore the modes for only jazz styles, but they are a great tool and inspiration for writing melody and fleshing out rich harmony.
For further listening:
Theme from the movie ET, Jurasic Park, The Simpsons
