Death is the termination of all biological functions that sustain a living organism. Phenomena which commonly bring about death include biological aging, predation, malnutrition, disease, suicide, homicide, starvation, dehydration, and accidents or trauma resulting in terminal injury. Bodies of living organisms begin to decompose shortly after death. Death has commonly been considered as a sad or unpleasant occasion, due to having a bond or affection to the person who has died, or having fear of death, necrophobia, anxiety, sorrow, grief, emotional pain, depression, sympathy, compassion, solitude, or saudade. The most common cause of human deaths in the world is heart disease, followed by stroke and other cerebrovascular diseases, and in the third place lower respiratory infections.