In the early 20th century, a number of psychologists were looking at a way to measure intelligence. Out of this work came about the intelligence quotient score or commonly known as IQ. The term "IQ," is a translation of the German words Intelligenz-Quotient . It was first coined by the German psychologist William Stern in 1912.
In order to know what one's IQ score is, a test called the IQ test has to be taken. The test contains a variety of questions ranging from topics covering mathematics, language, creativity etc. The test has to be completed in a set time and it's under supervision.
IQ test can come in various forms with some test containing a single type of question to others with several different sub tests. No matter which test is used, they will provide the overall scores as results.
The results from the test are then used to classify people into various intelligence categories. The system used for such classification is commonly known as the Stanford-Binet system.
The following result below of IQ scores indicates the different intelligence categories:
Under 70: Very mentally retarded
71-80: Mentally retarded
81-90: Slightly slow to grasp change
91-110: Normal level of intellect
111-120: High Intelligence
121 - 150: Very high intelligence
150++: Exceptional intelligence
Hence looking at the above, a person with an IQ of 120 is still considered to be more intelligent than someone with an IQ less than 120. This classification is generally still valid today. In fact we usually describe someone whom we considered smart and intelligent as a person with a high IQ.
The IQ classification system is criticized by many. It is argued that the IQ test is not complete and it does not measure all areas of intelligence. Other areas of intelligence includes emotional, social, intuitional etc. Then there are others who criticize the system as simply outdated and biased.
Due to the criticisms and controversy surrounding the IQ system, the American Psychology Association (APA) formed a task force in 1995 to look into this. The task force made a number of conclusions in response to the criticisms but more importantly it concludes that the IQ scores and the system developed more than a century ago is still valid today.