Q.Expand IUCN. What is the Red Data Book?

[!TLDR] IUCN = International Union for Conservation of Nature; the Red Data Book is its global list of species' conservation status. …

[!ANSWER] IUCN = International Union for Conservation of Nature; the Red Data Book is its published record of species' extinction risk.

The IUCN is an international body dedicated to conservation of nature and natural resources. One of its central, best-known outputs is the Red Data Book, also known as the Red List, which assesses and documents the conservation status of species worldwide using a standard set of categories reflecting how close a species is to extinction — ranging through categories such as Least Concern, Near Threatened, Vulnerable, Endangered, Critically Endangered, and finally Extinct. …

• Writing the wrong expansion for IUCN (e.g. confusing it with UNEP or WWF).
• Describing the Red Data Book as itself a law or protection measure, rather than …