Wikipedia
The SonneMondSterne Festival (short SMS) is an open-air festival featuring electronic dance music. The festival lasts three days and takes place on the second weekend of August in Thuringia at the Bleilochtalsperre near Saalburg-Ebersdorf.
The first festival was in 1997 with 2,500 people. The 15th festival in 2011 reached 35,000.
To reduce the time in between the festivals the organizer started the Wintercircus in 2001 and 2002 which took place in February. Due to the success of Wintercircus they moved it in April 2003 and renamed it to SonneMondSterne presents Camp Music. 2004 was the last Camp Music.
Since 2007 every festival is named with an additional "X", it stands for the Roman numeral ten. Therefore 2007 was as SMS.X1 the eleventh event.