There are two artists called I.O.S. One is a Detroit native also known under other aliases like Erik Travis, The Other Side of Space and Sound Of Mind. I.O.S. stands for Industry Of Sound.
The other I.O.S. is a Dutch band which mostly makes music called Nederpop, meaning it's pop with Dutch lyrics, as described by the leadsinger: "Nederpop with a sharp edge". The band was founded in Groningen in the province with the same name in the nothern region of the Netherlands. Their first big hit was released in 1997 and called "Voltooid Verleden Tijd". Almost 10 years later they're still going strong.
Orinally their name was Is Ook Schitterend (which means 'Is wonderful too'), which was later abbreviated to I.O.S.