Around the turn of the 20th century the budding field of psychology became interested in the idea of intelligence. The English created the field of psychometry, hoping to substantiate the idea of social Darwinism by showing the the upper classes were more intelligent than the lower. William Stern, a German psychologist, was the first person to use the term inteligenz quotient (German for intelligence quotient).
In 2010, the IQ test can be taken written or orally. Some tests are based on pure reasoning and some include things like basic math. Free online tests are available. However, for an accurate score contact an organization such as Mensa and have the test administered and corrected by a qualified person.
Psychologists have a conflicting view on what a genius actually is. However, a score of 140 or higher on a correctly administered IQ test is generally accepted as the bottom line genius. To put that into perspective, the mean average IQ in the United States is 98.