The three main areas of difficulty which all people with autism share are difficulty with social communication, social interaction & social imagination.
Source: What is autism? @ The National Autistic Society
Video
Further help
Image "Emotions3" by allyaubry☆ - http://www.flickr.com/photos/allyaubryphotography/2535453766/lightbox/. Licensed under CC BY 2.0 via Wikimedia Commons.
