What is very mild autism, and how does it affect a child?

Not defined. We do not have objective measures for telling whether a child's autism is "mild, " "moderate, " or "severe" and no agreed-upon system. Typically, "mild" is used to refer to a child with normal or better IQ who has some social withdrawal especially with peers, some language oddities, and some unusual behaviors but who is functioning pretty much at age level without a lot of supports.