It has been presumed that before the discovery of the pattern of symptoms now known as autism, that people did exist with the syndrome, and were lumped together either with the mentally retarded or the insane. We might expect to have inherited sufficiently-detailed descriptions of such people that we would be able to see a pattern suggesting autism among them, but there have not been many descriptions that suggest autism. One such description is of a boy found in the 19th century and named Victor. At the time, some assumed he had grown up without human contact in the forest. The story was recorded in the book The Wild Boy of Aveyron.
Leo Kanner published his first paper identifying autistic children in 1943, asserting he had noticed such children since 1938 (see reference to Kanner, "Autistic Disturbance of Affective Contact", see Selected Articles section below). Before Kanner noticed and recorded a pattern of symptoms, such children would be classified as emotionally disturbed or mentally retarded. Kanner observed that these children often demonstrated capabilities that showed that they were not merely slow learners, yet they didn't fit the patterns of emotionally disturbed children. Thus he invented a new category, which he called Early Infantile Autism, which has since sometimes been called Kanner's Syndrome. Hans Asperger (see section Well Known Researchers and Practicioners and reference to Asperger, "Autistic Psychopathy in Childhood" in Selected Articles section below) essentially made the same discoveries at the same time, independently of Kanner, but the patients he identified all had speech, so the term Asperger's Syndrome or Asperger Syndrome is often used to label autistic people who have speech.
Note that before before Kanner incorporated it into his label, the word "autism" already had a meaning: "escape from reality" (coined, I think, by Eugen Bleuler in 1912, who had already coined the term "schizophrenia"). Kanner borrowed Bleuler's term either because Kanner indeed believed the children were trying to escape from reality, or he felt that whatever was going on, the children gave that impression. Today, one hears the word autism in the context of Kanner's syndrome much more often than one hears it used with Bleuler's original meaning, and someone who regularly deals with Kanner's syndrome might misunderstand when the word is used in its original sense. For example, if a psychologist says "I sense some autism in this patient," s/he could be using established terminology to say the particular patient is escaping from reality, yet s/he would not necessarily be talking about someone who suffers from the developmental disorder that this FAQ is about.
After Kanner and Asperger's discovery, parents were observed to treat their autistic children without the warmth and affection which is normally observed between parent and child. Freudian psychology had a ready-made theory waiting for this syndrome and this observation: that if certain basic psychological bonds between parent and child fail to form that the child will fail to progress. A Freudian theory of autism remained in vogue in the 50s and early 60s. Though the theory fit Freudian psychology hand-in-glove, there are two obvious alternative possible explanations that the Freudian theory dismisses: one is that the parents' observed stilted interaction with the child was the result of the child's Autistic behavior; the other is that Autism is an extreme instance of a genetically-inherited personality trait that was present to a milder extent in such observed parents.
Based upon psychological theories of the basis of autism, some children were removed to their parents' home and put in foster care to see if they would recover. When this proved insufficient to cure them, some attempts were made to bring children through psychological states which they missed out on by virtue of being in a dysfunctional family. Some success has been reported (as has been reported for every treatment ever put forward) but no clear-cut success that would lead to universal, long-term adoption of the methods.
Above and beyond the distinction between the concept that Bleuler coined the word "autism" to label and the syndrome that is the subject of this document, the syndrome has been broadened somewhat since Kanner first published his paper. Kanner reported a rate of occurrence of 1 in 10000 whereas the ASA states the rate as 15 in 10000. Kanner first identified people who were clearly not mentally retarded (since this was the unexplained group of people at the time). Since then, it has been observed that some mentally retarded people have autistic symptoms whereas others don't; so it is thought that the conditions overlap. This explains some of the difference in the reported rates of occurrence, though some now claim that it doesn't fully explain it.
Other terms that have been applied to what we now call "autism". Childhood schizophrenia, infantile autism, Aspergers Syndrome, Kanner's Syndrome. Probably lots of autistic people used to be termed retarded, or schizophrenic, though obviously those terms (as then used) were not as specific as our current "autism" label.
The parents of autistic children are naturally less-than-objective about their own roles in the cause of their childrens' conditions. In the 60s, this was fueled by a widespread belief that the condition was caused by the way the parents treated their children. When evidence to the contrary (see section Theories) was uncovered yet not widely known, parents had to act as their own advocates. Parents still sometimes find themselves in the position of trying to explain how the fault does not lie with themselves since the general public's information on autism is still sometimes dated or wrong.
There remain a lot of controversies about treatment and probably have been from almost the first. See section above, "Controversies".
This article and book, written by a prime advocate of the Freudian theory of the cause of autism were highly influential in attitudes about Autism for a long time.