iiO (sometimes written as IIO, pronounced "eye-oh") is a New York City based house music act consisting of producer/songwriter Markus Moser and singer/songwriter Nadia Ali. iiO are best known for their 2001 hit "Rapture (Tastes So Sweet)". The name iiO is derived from the Sony PC laptop model VAIO, on which the duo was creating much of their early work, and the duo was in fact first known as Vaiio.

After "Rapture" was released, the duo followed suit with "At the End" in 2002, "Smooth" in 2003, and "Runaway" in 2004.

iiO's first album, "Poetica", was delayed several times and released independently in March 2005 on Made Records, and worldwide in June 2006.

By the time the album was released Nadia Ali had left iiO to pursue a solo career, while Moser continues to release material featuring her on the vocals. These included the single "Kiss You", which was released to promote the album, followed by "Is It Love?". Moser followed these with "Rapture 2007" and "Reconstruction Time: The Best of Iio Remixed" in 2007, and finally "Rapture Reconstruction: Platinum Edition in 2008.

iiO re-emerged from hiatus in December 2010 with Moser releasing new remixes of the band's second single "At The End (Metropolitan Mix)". Moser released a second album, "Exit 110" on April 19, 2011 featuring Ali on vocals. It was announced that Exit 110 will be iiO's final project and while Moser had doubts about using material Ali recorded before she left iiO, it was decided to release a new album due to a demand by fans.