Suicide is the act of intentionally causing one's own death. Mental disorders, physical disorders, and substance abuse are risk factors. Some suicides are impulsive acts due to stress, relationship problems, or harassment and bullying. Those who have previously attempted suicide are at a higher risk for future attempts. Effective suicide prevention efforts include limiting access to methods of suicide such as firearms, drugs, and poisons; treating mental disorders and substance abuse; careful media reporting about suicide; improving economic conditions; and dialectical behaviour therapy (DBT). Although crisis hotlines are common resources, their effectiveness has not been well studied.