What is autism?

At a glance

  • Challenges with social interaction and communication are common.

  • Autism can look different from person to person.

  • Autism may co-occur with ADHD and sensory processing issues.

Autism is a neurodevelopmental disorder that affects how people communicate and interact with others and the world around them. It’s lifelong — you don’t grow out of it.

Autism often co-occurs with other conditions, like ADHD and learning disabilities. They share common challenges with social skills and communication, including:

  • Trouble reading nonverbal cues or picking up “unwritten” social rules
  • Difficulty participating in conversation 
  • Not always being able to modulate (control how loud you speak, or in what tone)
  • Taking language literally and not always understanding puns, riddles, or figures of speech  

Another common sign is what’s known as stereotyped behavior. This may look like having a “special interest” around a certain topic or object. Or it can refer to repetitive behaviors and movements like:

  • Arm flapping or rocking (sometimes called stimming)
  • Repeating certain sounds or phrases (sometimes called echolalia)

There’s a lot of variation in how autism presents from person to person. Some people communicate by speaking. Others use nonverbal communication. There’s also a wide range in intellectual and self-care abilities. An autism diagnosis reflects this by using Support Levels of 1, 2, or 3. These levels show how much support a person needs, with 3 as the highest level.  

People talk about autism in different ways. Doctors and schools often use the term autism spectrum disorder (or ASD) and person-first language (“a person with autism”). Some people with the diagnosis prefer identity-first language and may call themselves autistic.

Rather than calling autism a disorder, some in the autism community embrace neurodiversity. This concept says conditions like autism are neurological variations that are simply part of human difference.

Dive deeper

About the author

About the author

Amanda Morin is the author of “The Everything Parent’s Guide to Special Education” and the former director of thought leadership at Understood. As an expert and writer, she helped build Understood from its earliest days. 

Reviewed by

Reviewed by

Elizabeth Harstad, MD, MPH is a developmental-behavioral pediatrician at Boston Children’s Hospital.