The first historically significant feature of Durkheim's approach to suicide is that he was trying to put the studying of it on a scientific sociological basis, despite the fact that in his time it was usually considered in light of religious prohibitions by churches that defined suicide as a mortal sin.
The first element of his essay is that he defines suicide as not just the act of killing oneself, but doing so in full knowledge that death will result; thus his definition would exclude reckless behavior or people hallucinating on drugs.
His next step is arguing that suicide can properly be studied as a sociological phenomenon, and not simply as an individual pathology. He does this by reviewing alternative theories of suicide, including ones based on climate and psychology, and shows that these do not fully account for the variations in suicide rates across cultures. Instead, he proposes three categories of suicide, egoistic, altruistic, and anomic.
Durkheim next shows that suicide rates vary by religion and degree of religious and community integration, showing that egoistic suicide is associated with a high degree of individualism and weak connections with community, although compared to this form of egoistical suicide, he also notes that tightly knit communities can give rise to altruistic suicides, where the individual's life is sacrificed for the good of the community as a whole. Anomic suicide occurs in times of crisis, often in response to a disconnect between aspirations and circumstances.
Durkheim recommends a strengthening of social bonds as a way to reduce the incidence of suicide.