Refers to a broad range of conditions characterized by challenges with social skills, repetitive behaviors, speech and nonverbal communication
When you encounter someone with autism they will usually avoid eye contact, get upset about relative changes in a schedule, or they do get unexpected reactions to sounds, taste, touch and smell.
It is hard for a person with ASD to transition into new tasks if they are not prompted or given a visual schedule. Some ASD's rely on pre notifications just so that gives them enough time to adjust to the transition before it happens.
There is no specific way to tell if you child has autism just by looking at them. There could be certian things your child does such as: be repetative, moving hands and legs constant, or even just not talk by the time they are 3 years old.
Always consult with a doctor about when and if you should get your child evaluated for autism.