Suicide (deaths due to self-inflicted injury) was often and in some places still is considered to be a sin or a crime. Now it usually recognised as being due to mental illness (psychiatric disorders), and is the commonest cause of death amongst people with depression, manic-depression, and schizophrenia. Mentally ill people are far more a danger to themselves than to other people. A tendency has developed to ascribe all suicides to mental illness. When circumstances are such as to make severe depression a natural response, it is sometimes classed as an illness called reactive depression. When suicide is a response to imprisonment without hope, impossible economic conditions, ill treatment and other obvious causes, it would be better to class the death as due to the obvious cause rather than due to a mental illness.
The data here shows that people are more at risk of being killed by themselves than deliberately by other people, but even more likely is being killed in a road traffic accident.
The International Classification of Diseases separates suicide into how it was commited rather than why. The method used to commit suicide depends partly on the availability of means - guns, high buildings to jump off, poisonous coal gas, tablets etc. There are often differences between the methods chosen by men and by women.
In 2002 Suicide caused 4.2% of deaths in adults aged 15 to 59 years and 1.8% of all deaths in rich territories.
Global Burden of Disease estimated in 2002 Suicide to cause 2.3% of all Rich territory burden of disease.
Suicide caused 1.5% of all deaths worldwide in 2002, an average of 140 deaths per million people per year.