Autism is a very wide spectrum, and each child/person will probably need different types of help. Do remember, that most autistic children will take instructions very literally.
When I ran a children's gymnastic club, we would tell the children to 'sit down on the floor'. Some autistic members took this as meaning they had to keep moving around constants in order 'to sit down on ALL of the floor'.
Yes, as Minimoon says, often have high level of sensory and problems which makes it painful and difficult for them to fit in to ordinary conditions.
But....to make you feel better, let me tell you about my eldest g.child. Realised he was autistic when he was quite young. Highly intelligent, his social skills never really advanced much beyond those of the average 3-year old. Got through primary school, with a dedicated classroom assistant - some serious problems. In the playground he started to hit other children just before the end of break time. Then it was realised that, for some reason, he felt he HAD to be third in the line-up, so would punch his way into that position.
Secondary school was dreadful, even though a good SENCO department. By half way through his first year he had been suspended so many times, and was being kept away from other pupils even when in school. He started down the road towards clinical depression.
Yes, I said it is a Good Story - so his parents fought and got him a place in a special school for autistic children, even though this mean him having to go as a weekly border.
Left there with an excellent handful of good GCSE results - and - even more important, a raft of self-management techniques. Went to local FE college where he collected four A levels (B A A A), and a place at the best Uni for his chosen subject of Chemical studies. Even in these strange times, he has settled happily there into halls, and is enjoying his studies.
He has made friends, and is enjoying life and will, undoubtedly, get an excellent degree and be a useful and production member of society.
His social skills are still way behind his years, at 20 years old, he has still not ever had any form of sexual relationship or desires one.