The following external site explains our knowledge to date in these areas:
THE NEUROSCIENCE OF INTELLIGENCE

» The idea of g

» Types of Intelligence

» Intelligence, Heredity, and Environment
History
Evidence for Nature
Evidence for Nurture
Comments on Research
Conclusion

» Neuropsychological Testing
Normal Intelligence
Abnormal Examination and Brain Trauma
Personality

» Spectroscopy Data

» Disorders related to Intelligence

» Gender Differences
Self-Estimated Intelligence
Anatomical Differences
Gray vs. White Matter

» Artificial Intelligence
A Timeline of AI
Ancient History of AI
Modern History of AI
The Future of AI

» Age and Intelligence
Areas of Function
Effects of Lesions

Gardner (1984) proposed that rather than a ‘g’ or general factor being responsible for an individual’s ability and therefore performance at work, multiple intelligences are responsible.

Read a summary of Gardner’s theory of multiple intelligences here

Also see Howard Gardner’s home page at: http://pzweb.harvard.edu/PIs/HG.htm

The following external link provides a multitude of resources that relate to the explanation and discussion of the ‘g’ factor of intelligence. Originally coined by Charles Spearman, ‘g’ stands for general:

Intelligence and Spearman’s ‘g’ factor

Hans-Georg Michna explains how IQ is defined in this external article:

The Definition of IQ

IQ = Intelligence Quotient

The following external resource provides an in-depth look at the thing that we call intelligence:

Intelligence: Knows and Unknowns
Report of a Task Force established by the Board of Scientific Affairs of the American Psychological Association.