Autism spectrum disorder (ASD) is the name for a range of similar conditions, including Asperger syndrome, that affect a person's social interaction, communication, interests and behaviour.

In children with ASD, the symptoms are present before three years of age, although a diagnosis can sometimes be made after the age of three.

It's estimated that about 1 in every 100 people in the UK has ASD. More boys are diagnosed with the condition than girls.

There's no "cure" for ASD, but speech and language therapy, occupational therapy, educational support, plus a number of other interventions are available to help children and parents.  People with ASD tend to have problems with social interaction and communication.

In early infancy, some children with ASD don’t babble or use other vocal sounds. Older children have problems using non-verbal behaviours to interact with others – for example, they have difficulty with eye contact, facial expressions, body language and gestures. They may give no or brief eye contact and ignore familiar or unfamiliar people.

Children with ASD may also lack awareness of and interest in other children. They’ll often either gravitate to older or younger children, rather than interacting with children of the same age. They tend to play alone.

They can find it hard to understand other people's emotions and feelings, and have difficulty starting conversations or taking part in them properly. Language development may be delayed, and a child with ASD won’t compensate their lack of language or delayed language skills by using gestures (body language) or facial expressions.

Children with ASD will tend to repeat words or phrases spoken by others (either immediately or later) without formulating their own language, or in parallel to developing their language skills. Some children don’t demonstrate imaginative or pretend play, while others will continually repeat the same pretend play.

Some children with ASD like to stick to the same routine and little changes may trigger tantrums. Some children may flap their hand or twist or flick their fingers when they’re excited or upset. Others may engage in repetitive activity, such as turning light switches on and off, opening and closing doors, or lining things up.

Children and young people with ASD frequently experience a range of cognitive (thinking), learning, emotional and behavioural problems. For example, they may also have attention deficit hyperactivity disorder (ADHD), anxiety, or depression.