Autism is a brain disorder that begins in early childhood, usually within the first three years of life and persists throughout adulthood. It affects crucial areas of development and exhibits following symptoms like:
learning difficulties i.e. he lacks in ability to learn inductively from surrounding events,
communication or speech problems,
difficulty relating to people, marked by a lack of awareness of the feelings of others, indifferent to parents
lack of social interaction,
short attention span,
not exhibiting creative or imaginative play,
performing actions that are often repetitive and unchanging like twirling objects or rocking,
reacting extremely to changes in the immediate environment.

Autistic children appear to lack the ability to see things from another person's perspective, a behavior cited as exclusive to human beings above the age of five and possibly in some primates.

Autistic traits continue into adulthood, but vary in severity. Some adults with autism do well, earning college degrees and living independently. Others never develop the skills of daily living, and may be incorrectly diagnosed with a variety of psychiatric illnesses.

Autism is a pervasive developmental disorder with an unknown origin. It is a bioneurological disorder and not a mental illness, which affects the functioning of the brain. Some theories suggest that it may be caused by genetics, viral and/or chemical exposure during pregnancy. Diagnosis is based on a list of psychiatric criteria as well as a series of standardized clinical tests are also used.

Surprisingly some autistic individuals may be outstandingly good at some kinds of mental manipulations for example, arithmetical calculations, music, drawing etc.

With intense therapy, practice and schooling, some children diagnosed with autism can improve their social and other skills to the point where they can fully participate in mainstream education and social events, but there are no indications that a cure from autism is possible with current technology or advances in medicine.

Asperger's syndrome and developmental delay syndromes are two of the related categories of Autism. These syndromes exist because of brain circuitry problems.

A key indicator to physicians making a proper assessment for autism would include looking for symptoms found in 'sensory integration dysfunction', where children will exhibit problems such as oversensitivity or under-reactivity to touch, movement, sights, or sounds; physical clumsiness; poor body awareness; a tendency to be easily distracted; impulsive physical or verbal behavior; an activity level that is unusually high or low; not unwinding or calming oneself; difficulty learning new movements; difficulty in making transitions from one situation to another. Autistic people may experience difficulty in hearing certain people's voice while others' are louder than usual.