Autism Spectrum Disorder (ASD) is the name given to a group of disorders that influence the social interaction and behavior of a person, according to the NHS.
The condition is much more common than people think, with 700,000 autistic people in the UK.
The signs and symptoms of autism vary from patient to patient, extra charity The National Autistic Society (NAS).
But the most important warning signs to watch out for are generally persistent problems with social communication and repetitive behavioral patterns.
People can be diagnosed with autism if they are very young – in some cases, from the age of two.
One of the headboards of a child on the autism spectrum is that the parent does not draw attention to an object, NAS said. This may mean that there is no indication of a toy or book with which they want to play.
As an alternative they can draw the attention of their parents to it, but later than expected.
Resisting change, or not wanting to do something different, can also be a sign of autism, the charity said.
Some patients can also perform activities in a repetitive manner, it said. This can include arranging objects in a certain way.
"Some of the most important signs that a child may be on the autism spectrum include carrying out activities repeatedly, for example always playing the same game, or repeatedly feeding toys in a certain order," said NAS.
"The characteristics of autism vary from person to person, but to make a diagnosis, a person will usually be judged as someone who has persistent problems with social communication and social interaction, and limited and repetitive patterns of behavior, activities, or interests since early childhood. "
These symptoms must be such that they limit and affect the daily function, according to the charity.
If problems with social interaction or social communication become clear, this can be a sign that the child is on the autism spectrum.
Biting, pinching, kicking or self-damaging behavior can also be signs of the condition.
Talk to a doctor if your child shows signs of an autism spectrum disorder, the NHS said.
ASD can also be diagnosed in adults if their condition is not recognized as a child.
If the diagnosis of ASD is made, the patient and his family can determine which support they need.
There is no cure for the condition, but there are ways to improve communication skills and promote social development.
More than one in 100 people in the UK is autistic. Men seem to have more ASD than women.
Visit www.autism.org.uk for more information about autism or the NAS.