Suicide is the act of intentionally causing one's own death.^[1] Risk factors include mental disorders such as depression, bipolar disorder, schizophrenia, personality disorders, alcoholism, or substance misuse.^[2][3] Others are impulsive acts due to stress such as from financial difficulties, troubles with relationships, or from bullying.^[3][4] Those who have previously attempted suicide are at higher risk for future attempts.^[3] Suicide prevention efforts include limiting access to method of suicide, such as firearms and poisons, treating mental disorders and substance misuse, proper media reporting of suicide, and improving economic conditions.^[3] Although crisis hotlines are common, there is little evidence for their effectiveness.^[5]

The most commonly used method of suicide varies between countries, and is partly related to the availability of effective means.^[6]Common methods include hanging, pesticide poisoning, and firearms.^[3][7] Suicide resulted in 842,000 deaths globally in 2013 (up from 712,000 deaths in 1990).^[8] This makes it the 10th leading cause of death worldwide.^[2][9]

Approximately 0.5% to 1.4% of people die by suicide, about 12 per 100,000 persons per year.^[9][10] Three quarters of suicides globally occur in the developing world.^[3] Rates of completed suicides are generally higher in men than in women, ranging from 1.5 times as much in the developing world to 3.5 times in the developed world.^[11] Suicide is generally most common among those over the age of 70; however, in certain countries those aged between 15 and 30 are at highest risk.^[11]There are an estimated 10 to 20 million non-fatal attempted suicides every year.^[12] Non-fatal suicide attempts may lead to injury and long-term disabilities. In the Western world, attempts are more common in young people and females.^[10]

Views on suicide have been influenced by broad existential themes such as religion, honor, and the meaning of life.^[13][14] The Abrahamic religions traditionally consider suicide an offense towards God due to the belief in the sanctity of life.^[15] During the samurai era in Japan, a form of suicide known as seppuku was respected as a means of making up for failure or as a form of protest.^[16] 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 the family and society.^[17] Suicide and attempted suicide, while previously illegal, are no longer in most Western countries.^[18] It remains a criminal offense in many countries.^[19] 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.^[20] The word is from the Latin suicidium, which means "the killing of oneself".^[21]