IQ, which stands for "Intelligence Quotient," is a standard score that tells you how much smarter or less smart than your peers are. The average score for this group is 100. By giving the same test to a huge group of people from all walks of life and then getting the average, the IQ number is found. 

For the first time, in 1912, psychologist William Stern used the formula "mental age to chronological age x 100" to show IQ. Let's say someone was 10 years old and thought like a 10-year-old, their IQ would be 100. But if, say, they were 13 years old instead of 10, their IQ would be 130.

What do IQ tests look like?

A normal IQ test includes several tests that measure intelligence, such as the ability to recognize patterns, remember things quickly, do math, and think critically. People often get the wrong idea about IQ tests, thinking that they test all the information you've learned over the years. Instead, they test your ability to learn. 

The first IQ test was made in the early 1900s. Since then, it has changed a lot. In the same way that they tested people's ability rather than anything they had learned in the past, their goal hasn't changed, and neither has the way they do it. 

The IQ test has been changed many times, but the Wechsler Adult Intelligence Scale (WAIS) is the one that is most often used. This test, which was made in 1955, was different from earlier IQ tests that looked at different mental skills, like verbal, numerical, spatial, and reasoning intelligence. There has been a change to this test, the WAIS-IV since it was first made. 

There are 10 subtests and five extra tests in the WAIS-IV. A verbal comprehension scale, a perceptual thinking scale, a working memory scale, and a processing speed scale are the four different types of intelligence that the test measures. Then, a person is tested with a group of friends to get a more accurate score, with two-thirds of the scores being in the normal range, which is between 85 and 115.