Dyslexia is a brain-based (i.e., neurobiological) learning disability that inhibits a person’s ability to read. Primary areas of difficulty are word recognition and reading fluency, spelling, and writing.
According to the National Institute of Child Health and Human Development:
"Dyslexia is a brain-based type of learning disability that specifically impairs a person’s ability to read. Individuals with dyslexia typically read at levels significantly lower than expected despite having normal intelligence. Although the disorder varies from person to person, common characteristics among people with dyslexia are difficulty with phonological processing (the manipulation of sounds), spelling, and/or rapid visual-verbal responding. Dyslexia can be inherited in some families, and recent studies have identified a number of genes that may predispose an individual to developing dyslexia."
A similar definition provided by the International Dyslexia Association describes it as follows:
“Dyslexia is a specific learning disability that is neurobiological in origin. It is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities. These difficulties typically result from a deficit in the phonological component of language that is often unexpected in relation to other cognitive abilities and the provision of effective classroom instruction. Secondary consequences may include problems in reading comprehension and reduced reading experience that can impede growth of vocabulary and background knowledge.”
"What is Dyslexia?" - a great video by Kelli Sandman-Hurley and Marc Kristoforidis, presented by TED-Ed.
The 1in5 Initiative is an advocacy group for people and families touched by dyslexia. Watch this empowering video and visit http://explore1in5.org/