A dark-sky preserve (DSP) is an area, usually surrounding a park or observatory, that restricts artificial light pollution. The purpose of the dark-sky movement is generally to promote astronomy. However, astronomy is certainly not the only objective of conserving a dark sky. A dark night sky is associated with many facets of history, philosophy, religion, societal development, poetry, song, mathematics, and science. Different terms have been used to describe the areas as national organizations have worked independently to create their programs. The International Dark-Sky Association (IDA) uses International Dark Sky Reserve (IDSR) and International Dark Sky Park (IDSP). A third designation, International Dark Sky Sanctuary, was introduced in 2015. History An International Dark-Sky Association (IDA) was founded in 1988 to reserve public or private land for an exquisite outlook of nocturnal territories and starry night skies. These reserves are specifically conserved for its scientific, natural, educational, cultural, heritage and public enjoyment. In 1993, Michigan became the first state in the United States to designate a tract of land as a "Dark Sky Preserve" at the Lake Hudson State Recreation Area. In 1999, the first permanent preserve was established at Torrance Barrens in the Muskoka region of southern Ontario. The IDA recognizes and accredits dark-sky areas worldwide, in three categories. The Mont Mégantic Observatory in Quebec is the first such site to be recognized (in 2007) as an International Dark Sky Reserve. IDA recognized Natural Bridges National Monument in Utah as the world's first International Dark Sky Park. In 2015, the IDA introduced the term "Dark Sky Sanctuary" and designated the Elqui Valley of northern Chile as the world's first International Dark Sky Sanctuary. The Gabriela Mistral Dark Sky Sanctuary is named after a Chilean poet. It is generally understood that a dark-sky preserve, or dark-sky reserve, should be sufficiently dark to promote astronomy. However, this is not always the case. The lighting protocol for a dark-sky preserve is based on the sensitivity of wildlife to artificial light at night (ALAN). Canada has established an extensive and more stringent standard for dark-sky preserves, that addresses lighting within the DSP and influences from skyglow from urban areas in the region. This was based on the work of the Royal Astronomical Society of Canada. Dark Sky Places The IDA's Dark Sky Places program offers five types of designations: International Dark Sky Communities – Communities are legally organised cities and towns that adopt quality