Sites of Special Scientific Interest (SSSI) are the basic building block of site-based nature conservation legislation in the United Kingdom (Areas of Special Scientific Interest in Northern Ireland), and most other legal nature/geological conservation designations in Great Britain, including national nature reserves, Ramsar sites, Special Protection Areas, and Special Areas of Conservation, are based upon them. Sites notified for their biological interest are known as "Biological SSSIs", and those notified for geological or physiographic interest are "Geological SSSIs". Many SSSIs are notified for both biological and geological interest.