Underwater ecosystems characterized by reef-building corals. They are vital for marine biodiversity and coastal protection but are highly sensitive to environmental changes caused by dredging and pollution.

Describes landforms or islands formed by volcanic activity. For UPSC Geography, this helps understand geological processes, land formation, and the distribution of island nations like Mauritius.

The supreme authority of a state to govern itself and control its territory, free from external interference. The article highlights the need for states to actively maintain their sovereignty in the face of global power shifts and territorial revisionism.