Death is the permanent, irreversible cessation of all biological functions that sustain a living organism. The remains of a previously living organism normally begin to decompose shortly after death. Death is an inevitable, universal process that eventually occurs in all living organisms.
Death is generally applied to whole organisms; the similar process seen in individual components of a living organism, such as cells or tissues, is necrosis. Something that is not considered a living organism, such as a virus, can be physically destroyed but is not said to die.
As of the early 21st century, over 150,000 humans die each day.