TWAS, The World Academy of Sciences, until 2004 named Third World Academy of Sciences and TWAS, the academy of sciences for the developing world before September 2012, is a merit-based science academy uniting 1,000 scientists in some 70 countries. Its principal aim is to promote scientific capacity and excellence for sustainable development in the South (see North-South divide). Its headquarters are located on the premises of the Abdus Salam International Centre for Theoretical Physics (ICTP) in Trieste, Italy.