So, on what finger do you wear a promise ring? In the USA and the UK, the ring finger (fourth finger) of the left hand holds the greatest significance; engagement rings and wedding rings are worn on this finger almost without exception.
In biology and ecology, extinction is the end of an organism or of a group of organisms (taxon), normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively.
Extinction is when all members of a particular group die. Most often, we use it to discuss animal species. Many fear that the tiger is headed for extinction because of development and hunting. People are still trying to figure out what caused the extinction of the dinosaurs: many think it was because of an asteroid. When people cut down rain forests, it can lead to the extinction of many species. Although extinction can be natural or unintended, the word can also mean forced, planned killing.