The Diagnostic Statistical Manual was first published in 1952. It is now in its 5th edition and has seen some dramatic changes in its diagnostic criteria.
Some mental illness classifications from the past appear very surprising today, for example homosexuality. Before the DSM mental illnesses were still classified by physicians, psychologists and psychiatrists. Before the DSM there were a range of diagnosis like Hysteria, or Draptomania (the attempts of black salves to flee slavery) which are now considered highly problematic and in these cases sexist and scientifically racist. Prior to the DSM was the Mental Measurement Yearbook which also reviewed diagnosis and Psychological tests.
The DSM attempted to collect all known mental illnesses, review those with similar symptom presentation and collate a definitive set of diagnosis complete with definitions, symptoms and possible treatment.
The DSM was and continues to be highly popular and is used as the definitive text on diagnosis in western Psychology. However it has come under some critique from the anti-psychiatry movement.