In Britain, 'dyslexia' is often used in quite a general way to describe a range of specific learning difficulties related to underlying differences in processing sound, visual stimuli, symbols and movement. Sometimes dyspraxia (difficulty in coordinating movement) or dysgraphia (difficulty specifically with writing) or discalcula (difficulty with numbers) are separated out. In some counties many more fine distinctions are used to apply to particular combinations of difficulty and strength. It is not unusual for those with specific difficulties to experience two or more of these specific 'types' of difficulties; it is not yet really clear from the evidence how far these differently named conditions are part of an underlying broader syndrome, manifested in different clusters in each individual.
The term 'specific learning difficulties' (SpLDs) is sometimes used to indicate that a person does not find learning in general to be difficult. Rather, it is difficult to learn, perform or demonstrate knowledge and understanding under certain conditions for certain types of task. For this chapter, the term 'dyslexia' will be used most of the time as a shorthand to cover the broader range of difficulties. Although 'dyslexia' is a misnomer (it does not accurately describe the difficulties), using one term will make the text more readable.