A person's Intelligence Quotient (IQ) is, arguably, one of their most important characteristics. It is believed that you can predict a person's behaviour better from their IQ than from any other single piece of information about them. Job applicants worldwide are likely to be given a psychological test to determine how suited they are for a particular post, our children may be given ability tests if they seem to have problems at school or as part of a career counselling process and when the elderly are admitted to hospital a simple test is often used to alert physicians to the possibility of dementia. However, IQ is also an area of psychology rife with myth and misunderstanding. Is it really possible to describe all of a person's myriad abilities using one number, their IQ? What influences how well a particular person will perform in a test? Can we improve our performance on these tests through practice or training? The IQ Book aims to address these issues and many more.