A belt of rain-bearing clouds, the Inter-Tropical Convergence Zone (ITCZ), girdles the Earth’s tropical area throughout the year. The belt migrates with the Sun. Its arrival over the Indian subcontinent, usually in early June, heralds onset of the rainy Indian Summer Monsoon (ISM); withdrawal from the subcontinent, approximately in late September, marks end of the wet monsoon and start of dry season. While the ISM is a component of the global-scale ITCZ, its behaviour over the subcontinent is influenced by two local factors: interaction of the atmosphere with near-surface waters of the North Indian Ocean; and influence of topography of the East African Mountains, Himalayas, Sahyadris (Western Ghats), and Arakan Range on low-level atmospheric flow. This talk provides an oceanographer’s view of what makes the ISM happen, making the subcontinent habitable.