Acoustic: genre or movement?

Acoustic music was actually born out of the introduction of electric instruments into the music world. It basically means that the music is born out of the "pure" instruments with no electronic enhancements. Top artists include: Matt Costa, Peter Bradley Adams, Dispatch, Lifehouse, Paramore, and many more. This does not mean that these and other artists do not use any electric devices. In fact, many (if not all) use electronic amplifiers in their performances; to purify their sound and distinguish it from that of electronic nstruments many artists place a microphone in front of their instrument and have that device wired into an amplifier. Acoustic artists tend not to solely play in this style of music; many of these musicians split their talents between what is now commonly referred to as "unplugged" (a term coined in the '90s) and utilizing all musical instruments to perform.
Lifehouse: Broken
Margot & the Nuclear So and So's

Fun Fact: One of a lesser known acoustic artists has become known more for his acting in a blockbuster movie series known as The Twilight Saga. Robert Pattinson, best known for playing Edward in the vampire movies is also an accomplished talent that has mastered the piano & guitar. He does not seek to promote his music but did have two of his original songs placed into the first Twilight movie. His haunting lyrics take one inside the emotion behind the music. The links below are to the songs featured in the movie.

Rob Pattinson, Let Me Sign
Rob Pattinson, Never Think