atol

Atol is commonly a misspelling or variant of atoll, a ring-shaped island formed by coral reefs. An atoll typically encloses a central lagoon and lies low above sea level. The classic model of atoll formation, proposed by Charles Darwin, describes a progression from a fringing reef around a volcanic island to a barrier reef and finally an inward-growing reef forming a circular lagoon. Atolls are most characteristic of the tropical Indo-Pacific, with well-known examples in the Maldives, Kiribati, and the Marshall Islands. The term atoll can also appear in historical or non-English texts as a simplified spelling.

ATOL, capitalized, stands for Air Travel Organisers' Licensing, a UK government-backed consumer protection scheme administered by the Civil Aviation Authority. It covers many package holidays and some flight-inclusive bookings sold by travel organizers. Operators must hold an ATOL and provide customers with an ATOL certificate, which confirms the protection and cover limits. If an ATOL-protected operator fails, customers are entitled to refunds and/or coordinated repatriation; the scheme helps separate consumer funds from operator assets. ATOL protection is distinct from other forms of travel protection and does not apply to most independent flight or accommodation bookings.

Both uses of 'atol' reflect different domains—geography and consumer protection. In context, the correct meaning is usually clear from language, capitalization, and accompanying discussion.