The island was known in ancient times as Sinhale, Lanka, Lankadeepa (Sanskrit for "resplendent land"), Simoundou, Taprobane (from the Sanskrit Tamaraparni), Serendib (from the Sanskrit Sinhala-dweepa), and Selan. During colonization, the island became known as Ceylon (from Selon through the Portuguese Ceilao), a name still used on occasion. Its shape and proximity to the Indian mainland have led some to refer to the island as India's Teardrop.

The island of Sri Lanka lies within the Indian Ocean, with the Bay of Bengal to the northeast. It is separated from the Indian subcontinent by the Gulf of Mannar and the Palk Strait. According to Hindu mythology, a land bridge to the Indian mainland, known as Adam's Bridge, was constructed during the rule of Rama. It is now mostly submerged, with only a chain of limestone shoals remaining above sea level. According to temple records this natural causeway was formerly complete, but was breached by a violent storm (probably a cyclone) in 1480.

The pear-shaped island consists mostly of flat-to-rolling coastal plains, with mountains rising only in the south central part of the island. Amongst these are Adam's Peak and Pidurutalagala, the latter being the highest point at 2,524 m.

Mosque in GalleThe Sri Lankan climate is tropical, characterized by monsoons: the northeast monsoon lasting from December to March, and the southwest monsoon from June to October. The lowest gravitational field on Earth lies just off the coast of Sri Lanka. Sigiriya is considered the 8th wonder of the world.

The commercial capital is Colombo, but the administrative and legislative capital is located in nearby Sri Jayewardanapura (Kotte). Other major cities include Jaffna, Galle, and Kandy.