M.S. Raghunathan is a distinguished visiting professor at UM-DAE Centre of Excellence in Basic Sciences, University of Mumbai, Maharashtra, India. Earlier, he was at the Tata Institute of Fundamental Research (TIFR), Mumbai, India, from 1966–2006. After his retirement from the TIFR, he held the Homi Bhabha Chair Professorship of the Department of Atomic Energy, Government of India, from 2006–2011. He was a distinguished visiting professor at the Indian Institute of Technology Bombay. Mumbai, India. A distinguished mathematician, who has made significant contributions to the theory of algebraic groups and their discrete subgroups, has been a visiting professor at many universities in Europe, the USA, Japan and China. He is a fellow of the Royal Society and the World Academy of Sciences. He was an invited speaker at the International Congress of Mathematicians held in Nice, in 1970.