Suicide is the act of intentionally causing one's own death.[6] Mental disorders, including depression, bipolar disorder, schizophrenia, personality disorders, and substance abuse—including alcoholism and the use of benzodiazepines—are risk factors.[2][4][7] Some suicides are impulsive acts due to stress, such as from financial difficulties, troubles with relationships, or bullying.[2][8] Those who have previously attempted suicide are at a higher risk for future attempts.[2] Effective suicide prevention efforts include limiting access to methods of suicide—such as firearms, drugs, and poisons; treating mental disorders and substance misuse; proper media reporting of suicide; and improving economic conditions.[2][9] Even though crisis hotlines are common, there is little evidence for their effectiveness.[10][11]

The most commonly used method of suicide varies between countries, and is partly related to the availability of effective means.[12] Common methods of suicide include hanging, pesticide poisoning, and firearms.[2][3] Suicides resulted in 828,000 global deaths in 2015, an increase from 712,000 deaths in 1990.[5][13] This makes suicide the 10th leading cause of death worldwide.[4][14]

Approximately 0.5-1.4% of people die by suicide, roughly 12 per 100,000 individuals per year.[14][15] Three quarters of suicides globally occur in the low and middle income countries.[2] Rates of completed suicides are generally higher among men than among women, ranging from 1.5 times as much in the developing world to 3.5 times in the developed world.[1] Suicide is generally most common among those over the age of 70; however, in certain countries, those aged between 15 and 30 are at the highest risk.[1] Europe had the highest rates of suicide by region in 2015.[16] There are an estimated 10 to 20 million non-fatal attempted suicides every year.[17] Non-fatal suicide attempts may lead to injury and long-term disabilities.[15] In the Western world, attempts are more common among young people and among females.[15]

Views on suicide have been influenced by broad existential themes such as religion, honor, and the meaning of life.[18][19] The Abrahamic religions traditionally consider suicide as an offense towards God, due to the belief in the sanctity of life.[20] During the samurai era in Japan, a form of suicide known as seppuku (harakiri) was respected as a means of making up for failure or as a form of protest.[21] Sati, a practice outlawed by the British Raj, expected the Indian widow to kill herself on her husband's funeral fire, either willingly or under pressure from her family and society.[22] Suicide and attempted suicide, while previously illegal, are no longer so in most Western countries.[23] It remains a criminal offense in many countries.[24] In the 20th and 21st centuries, suicide has been used on rare occasions as a form of protest, and kamikaze and suicide bombings have been used as a military or terrorist tactic.[25]