Defining intelligence can be a tricky task. It can take many forms, and be difficult to assign a definition. Testing an individual's intelligence can also be tricky, because of the complexity it holds. There are many factors that are taken into account and many ways to compute a person's IQ. Intelligence testing has altered over the years, with the hopes of becoming more and more accurate.

It all started when Alfred Binet and Theodore Simon invented what is regarded as the first intelligence test. This is a tool that was developed to measure someone's overall thinking ability. The test required the participant to memorize pictures, know vocabulary, name familiar objects, repeat sentences and follow commands. Overtime there have been changes and modifications to the original intelligence testing.
Today, the IQ test is seen as one of psychology's biggest, and perhaps most controversial, accomplishments. The IQ test has been remarkably influential and is still used today. Wechsler Adult Intelligence Scale is the most popular test used today to test adult IQs. It consists of 15 subtests that assess different mental abilities. There are adapted versions to test children and adolescents. There are also culture-fair IQ tests. These tests do not depend on language and are seen to be less influenced by culture.
Overall, testing intelligence is a daunting task, but because of the advances and inventions in psychology, it is becoming easier and easier throughout the years.