Critical national infrastructure are the facilities, systems, physical sites, people, and processes that are necessary for keeping a country going. They are the sites on which daily life of a country’s citizens depend. Some sites may pose a security risk or danger to the public, like nuclear and chemical sites.
The UK has 13 different critical national infrastructure sectors, Chemicals, Civil Nuclear, Communications, Defence, Emergency Services, Energy, Finance, Food, Government, Health, Space, Transport and Water.