The Intelligence Quotient (IQ) is the score derived from an intelligence test. Developed in the early 20th century, the IQ test has evolved and been altered a number of times since then. IQ scores are used to determine and predict a number of factors such as education level, job performance and income.

IQ scores normally range from 1 - 175, and are broken into categories of intelligence. A score of 85 - 114 is considered to be the average IQ. A score below this IQ determines the extent of a mental disability and any score above this average determines the extent to which a person is gifted.

Since the test was created, average IQ scores have increased in most parts of the world by around 3 points per decade. It is believed that this has occurred due to improvements in nutrition, better education, heterosis, and a trend of smaller families. However many believe that modern education is directed at bettering IQ rather than general intelligence. Due to these progressively increasing scores, the IQ scores are renormalised to the mean of 100 to compare with existing scores.

The IQ has taken a great deal of interest from people all around the world and has been vigorously studied and tested to determine its relevancy and importance. In studies performed by psychologist Richard Haier has discovered that General intelligence and IQ have a direct link to the amount and allocation of gray matter in the brain. Other controversial studies have provided statistics proving differences in IQ scores can be caused by health, gender or race. In the past, IQ scores were often used as job requirements and employers would often make a high IQ an essential quality during the interview process. However in recent years, professionals in numerous fields of work have proved that there are more important factors than IQ for certain jobs, and studies into these measures are becoming more popular.

It was found that persons with a high IQ have lower adult morbidity and mortality. Morbidity is a term used to acknowledge a diseased state, or the existence of any form of disease and morality the likelihood that the person in question will die over a future period of time. It was also found that persons suffering from post traumatic stress, severe depression or schizophrenia are less common in high IQ bands. Although there is no direct difference between male and female average IQ scores, it has been discovered that male IQ scores have a much greater variance. There have also been a number of observations that prove significant differences in IQ across races. However many debates argue against this hereditary hypothesis, claiming that variations in IQ occur due to environmental reasons. It is also believed that IQ can be connected to social outcomes. An example is the connection found with those who committed juvenile offences and a lower than average IQ score.

The popularity of IQ tests is still very high around the world. Most people highly regard intelligence and are inclined to take the test in order to determine their score. However the testing process can be long and take up a lot of time that people do not have in this fast pace society. There are a number of organisations that have developed online IQ tests that are fast and can roughly determine a person's intelligence.