Intelligence Quotient, otherwise known as IQ, is a measure of your intellectual capacity. Intelligence is then assessed based on your individual score on an intelligence test--a score ranging between zero and 150+. The average adult's IQ score is 100, though a 15-point difference (a score of 85 or 115) is considered average as well; lower IQ scores indicate below average IQs, and higher IQ scores indicate above average IQs.
IQ tests originated in France when Alfred Binet was asked by French government to create a testing system for intelligence--one that would separate the less intelligent children from the normally intelligent children. This led to the development of a test known as the Stanford Revision of the Binet-Simon Scale of Intelligence (commonly referred to as the Stanford-Binet).
A variety of intelligence tests developed over the years; however, the most commonly used tests are the Stanford-Binet Scale of Intelligence, the Wechsler Adult Intelligence Scale (WAIS) and the Wechsler Intelligence Scale for Children (WISC).
The Wechsler Intelligence Scale for Children is now (as of 2009) in its fourth edition. Known as the WISC-IV, this test is designed for children aged 6 months to 16 years and 11 months. Children's IQ is mostly determined by their scores in verbal comprehension, perceptual reasoning through pictures, the ability to memorize and recall numbers, and how fast they process and organize information during tasks. Children's ages are taken into consideration when measuring for IQ.
The Wechsler Preschool and Primary Scale of Intelligence (WPPSI) is used as well; however, it is limited to use for children between ages 2 1/2 through 7 1/4.
The Wechsler Adult Intelligence Scale (WAIS) is the most commonly used IQ test for adults. Much like the WISC, the WAIS is in its fourth edition. The WAIS-IV is designed for individuals aged 16 and over. It measures verbal reasoning in addition to how well the individual interprets pictures, remembers and recalls numbers, and processes patterns and designs.
This test is often used in academic and clinical settings, where an individual can benefit in a number of ways. Academically, this may include placement in advanced or specialized classes; clinically, measuring a person's IQ can advise a clinician on how to approach diagnosis and treatment.
IQ tests will provide valuable information regarding your cognitive abilities. However, take into consideration your age, culture and socioeconomic status when interpreting your IQ scores, as IQ scores do not always account for these factors. Also, IQ is a measure of one's cognitive ability, and is not a predictor of how well a person will perform in school or work. Intelligence tests measure your abilities and the intellectual capacity you are born with, while achievement tests (such as the SAT) measure attainment and achievement. Do not assume that a poor score on a standardized test translates into low intelligence.