Extinction is the complete disappearance of a species from life. No more of that species is alive on the planet. It happens all the time; the normal rate of extinctions is called the background...
Mass extinction- More than 50% of the population went extinct in a short period of time. Background extinction- An average rate of extinction for a given time period.
A background extinction is the continuous extinction of individual species caused by climate change, disease, loss of habitat, and competitive disadvantages against other species. Background...