Autism is a lifelong developmental disability that can affect how people communicate, perceive the world and interact with others.
It is estimated around 1% of the population in the UK have Autism Spectrum Disorder (ASD) - that is 34,000 people in Wales.
Autistic children grow up to be autistic adults - the level and kind of support changes with each individual - and at different stages of their life.
The National Autistic Society says getting a timely diagnosis is key to helping people.
The NAS say without understanding, autistic people and families are at risk of "being isolated and developing mental health problems".
Often, autistic individuals have a high intelligence rate - but many struggle with maintaining employment.
Individuals can be affected with autism in a variety of ways but many have difficulty communicating socially including reading other people and understanding body language and intentions.
Other common traits include:
All this week, ITV Wales will be sharing the lived experiences of autistic adults to raise awareness of what it is like for some people on a day-to-day basis.
Professor Ian Walker is a retired university lecturer who was only diagnosed with autism at the age of 71.
He told his story on Wales at Six.