Einsteins IQ test Score was around 165, Bill Clinton's is 137, Bill Gates' is 160, George W Bush's is 125, and Madonna's is 140. But what is an IQ score in the first place?

An intelligence quotient, or IQ, is a score derived from one of several different standardized tests attempting to measure intelligence. The term "IQ," from the German Intelligenz-Quotient, was coined by the German psychologist William Stern in 1912 as a proposed method of scoring early modern children's intelligence tests such as those developed by Alfred Binet and Théodore Simon in the early 20th Century. Although the term "IQ" is still in common use, the scoring of modern IQ tests such as the Wechsler Adult Intelligence Scale is now based on a projection of the subject's measured rank on the Gaussian bell curve with a center value (average IQ test score) of 100, and a standard deviation of 15, although different IQ tests may have different standard deviations.

IQ test scores have been shown to be associated with such factors as morbidity and mortality, parental social status, and to a substantial degree, parental IQ quiz scores. While its inheritance has been investigated for nearly a century, controversy remains as to how much is inheritable, and the mechanisms of inheritance are still a matter of some debate.

IQ test scores are used in many contexts: as predictors of educational achievement or special needs, by social scientists who study the distribution of IQ quiz scores in populations and the relationships between IQ test score and other variables, and as predictors of job performance and income.

The average IQ test scores for many populations have been rising at an average rate of three points per decade since the early 20th century with most of the increase in the lower half of the IQ test range: a phenomenon called the Flynn effect. It is disputed whether these changes in scores reflect real changes in intellectual abilities, or merely methodological problems with past or present testing.