Number 19: Art Rock

As you might have guessed, this is a sub-genre of rock- it's like rock mixed with some avant-garde and classical music. These two types of music are often called art music, resulting in the name. Art rock is also seen as being a free-er version of rock and roll, with more experimental and conceptual work. The term 'art rock' is often used in place of 'progressive rock' (or vice versa)- however, it's noted that there are differences in the two.
Though not usually considered art rock themselves, the Beatles were a huge influence in the creation of the genre.
Emerson, Lake and Palmer (known as ELP), Electric Light Orchestra (ELO) and the Moody Blues were very involved in the development of art rock. As far as I can tell, the use of EL initials isn't related to the genre! ELP particularly were renowned for very lengthy pieces; the one I've chosen also happens to sound like it should be the soundtrack for a video game.

Mr Blue Sky- Electric Light Orchestra

Shadows On The Wall- The Moody Blues

The Score- Emerson, Lake and Palmer