'Hinduism' is an English word that was first used in 1816 and 1817 by Raja Rammohan Roy, an Indian social reformer. Rammohan Roy, a Hindu by birth and an eloquent critic of the faith as it was then practiced, used it to describe the religion of his ancestors who believed in the unity of God as 'real Hinduism' (Lorenzen 1999: 631). The word itself comes from the ancient Persian term 'Hindu', a derivation from 'Sindhu' (the name of the Indus river), which was originally used to characterize an inhabitant of the lands to the east of the Indus. How and when 'Hindu' with its ethno-geographical connotation came to mean a community with identifiable socio-religious beliefs and practices is less certain, although Al-Biruni in the eleventh century AD offered a precise and detailed account of such beliefs and practices. As the papers in this volume show, material traces that constitute the archaeology of Hindu worship and belief are observable in South Asia in the second half of the first millennium BC and in Southeast Asia beginning in the early-midfirst millennium AD. Hinduism remains a living religion, with more than 76 per cent of people in India, 85 per cent in Nepal and a very small percentage in Southeast Asia (as it lost its dominance in the thirteenth to fifteenth centuries and thus, for example, only about 5 per cent in Singapore, 2 per cent in Indonesia, though with more than 90 per cent of the Balinese, and a very small group of Chams in south-central Vietnam) continuing to describe themselves as Hindu. What are the forms of worship and ritual that mark out Hinduism as a religion? In an essay that bears the same title as this volume, the archaeologist Dilip Chakrabarti cites Alfred Lyall's description (based on his observations while employed in India from 1856 to 1861) of Hindu ritual behavior in India: