ATLAS is the world’s largest physics experiment and operates at the 27km Large Hadron Collider (LHC) (the world’s largest machine) located at CERN in Geneva. ATLAS is designed to study the fundamental constituents of the Universe with goals including understanding the origin of mass and the nature of dark matter. The ATLAS Collaboration comprises over 2500 members from 169 universities in 37 countries. Beams collided at 7 TeV in the LHC at 13:06 CEST, Geneva, 30 March 2010, marking the start of the LHC research programme. For more details see ATLAS homepage at CERN.