Hugh Hefner, who died aged 91 on Wednesday, "peacefully passed away from natural causes," according to a statement from his spokesperson.
It's a phrase we hear regularly in news reports, but what does it actually mean to die from natural causes?
When you hear those words used, it means the person has not been killed by any external factors. There was no foul play, they did not take their own life, and they weren't involved in an accident, such as a crash or drug overdose.
So it means there was some sort of natural disease process that led to death; whether it be heart disease, stroke, or something else. The coroner or medical examiner who makes the call might also list factors that contributed to the natural death on the death certificate.
That said, it's possible for natural causes to be triggered by a particular situation. If you are climbing a mountain and die from a heart attack, that's a natural cause but it might well be driven by the stress your body is under. But if a rock fall knocks you off a cliff face during the climb, that would be an external cause of death.
Natural causes are the most common cause of death. In the United States in 2017, eight of the ten top causes of death were diseases or other internal causes (the other two were "accidents" and suicide).
Sometimes, an autopsy might be required to determine that a death is natural, but other times it will not. If an old person dies and there are no visible signs of foul play or other evidence that would suggest an external cause, the official in charge may be able to deliver a verdict of natural causes without an autopsy.
If a much younger person dies, even if there is no visible evidence to suggest an external cause, an autopsy might be necessary; younger people are far less likely to drop dead without warning.
