A State of Trance 2004 is a trance music compilation album composed of various artists set together by Armin van Buuren as a continuous mix.

A State Of Trance (often abbreviated as ASOT) is the title of a weekly radio show hosted by prominent trance producer DJ Armin van Buuren. First airing in March 2001 on ID&T Radio (the predecessor of Slam!FM), the show takes the format of a two hour mix in which he plays new trance music, both promotional and commercially released. Selected tracks are announced during the show in order to help promote new artists and releases. Its radio-show/website combination has proven popular internationally, as fans—while listening to the radio-show—will converse in the website chat-rooms and forums, such as Digitally Imported, during the broadcast. The success of the show has also spawned to include several parties around the world. In 2011 the 500th episode of the show was celebrated by hosting five different parties on five different continents. ASOT 500 has been hosted in Johannesburg (South Africa), Miami (United States), Buenos Aires (Argentina), Den Bosch (The Netherlands), and Sydney (Australia) between March and April 2011.

Armin van Buuren (Dutch pronunciation: [ˈɑr.mɪn vɑn ˈby.rə(n)]), OON (born 25 December 1976 in Leiden, Netherlands) is a Dutch trance producer and DJ. Between 2007 and 2010, he was voted number one in DJ Magazine's annual top 100 list of the most popular DJs. In the 2011 list, he ranked in second place. Since 2001, Van Buuren has hosted a weekly radio show called A State of Trance, which claims to have around 15 million weekly listeners in 26 countries, which would make it one of the most listened-to radio shows in the world. His 2008 studio album, Imagine, entered the Dutch album chart at #1, a first for a dance music artist in Dutch music history.

Armin van Buuren was born in Leiden, Netherlands on 25 December 1976, but grew up in Koudekerk aan den Rijn. Van Buuren started making music when he was 14.^{[citation needed]} He was inspired by French electronic music composer, Jean Michel Jarre, and wished to become a great electronic music composer like Jarre.^{[citation needed]}

He finished high school at the Stedelijk Gymnasium Leiden in 1995, and left for college to study law at Leiden University. While studying law, Van Buuren's interest for making music blossomed, and he began working as a DJ in a local club called Nexus. As his musical career began to take off, he put his law degree on hold, although he did return to finish law school in 2003.