Short answers, pulled from the story.
Approximately 150,000 people die every day on Earth. This figure represents the most common event on the planet and defines the human condition through the statistic that 56 million people die per year as of the early 21st century.
The Uniform Determination Of Death Act in the United States defines death as the irreversible cessation of electrical activity in the whole brain. This conclusion was reached by the President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research in 1980.
Physician J.C. Ouseley claimed in 1895 that as many as 2,700 people were buried prematurely each year in England and Wales. Some estimates suggest the figure was closer to 800, reflecting the public fear of being mistakenly buried alive during the mid-18th century.
Biological aging is the largest unifying cause of death in the developed world, leading to various complications known as aging-associated diseases. In industrialized nations, this proportion approaches 90% of the roughly 150,000 people who die each day across the globe.
The jellyfish Turritopsis dohrnii, the hydra, and the planarian are organisms that exhibit negligible senescence and biological immortality. While these species can survive all calamities, they can still die from external forces or accidents rather than the effects of aging.