Short answers, pulled from the story.
Suicide is the 10th-leading cause of death worldwide, accounting for about 1.5% of all deaths. It resulted in 828,000 deaths globally in 2015, up from 712,000 in 1990, even as the age-standardized death rate fell by 23.3%.
Risk factors for suicide include mental disorders, substance misuse, physical illness, trauma, and social isolation. Major depression and bipolar disorder carry the greatest risk, with substance misuse the second most common factor.
Death by suicide occurs about 1.8 times more often in males than females globally, and three to four times more often in the Western world. Suicide attempts and self-harm, by contrast, are two to four times more frequent among females. China is the only country where the female rate is higher than the male rate.
Lithium reduces the risk of suicide in mood disorders by 87% in randomized controlled trials. The Caring Letters model, which mails brief personally signed letters to people after a hospitalized attempt, has also been proven in a randomized controlled trial to reduce deaths by suicide.
A review of 56 countries found hanging the most common method in most of them, accounting for 53% of male suicides and 39% of female suicides. Worldwide, about 30% of suicides occur from pesticide poisoning, mostly in the developing world.
The Werther effect is suicide contagion in which depictions of suicide increase its occurrence, named after the protagonist of Goethe's The Sorrows of Young Werther. Its opposite, the Papageno effect, named for a character in Mozart's The Magic Flute, describes how coverage of effective coping mechanisms may have a protective effect.
England and Wales decriminalized suicide through the Suicide Act 1961, and the Republic of Ireland followed in 1993. No country in Europe currently treats suicide or attempted suicide as a crime, though it remains illegal in some nations, including most Muslim-majority countries.