Dyslexia covers a wide range of language difficulties. In general, a person with dyslexia cannot grasp the meaning of sequences of letters, words, or symbols or the concept of direction. The condition can affect people of otherwise normal intelligence. Dyslexic children may reverse letter and word order, make bizarre spelling errors, and may not be able to name colors or write from dictation. It may be caused by minor visual defects, emotional disturbance, or failure to train the brain. New evidence shows that a neurological disorder may be the underlying cause. Approximately 90 percent of dyslexics are male.

The term dyslexia (of Greek origin) was first suggested by Professor Rudolph Berlin of Stuttgart, Germany, in 1887. The earliest references to the condition date as far back as 30 C.E. when Valerius Maximus and Pliny described a man who lost his ability to read after being struck on the head by a stone.