The Keirsey Temperament Sorter®-II (KTS®-II) is the most widely used personality instrument in the world. It is based on the Temperament Theory of David Keirsey as outlined in his tremendously fascinating books Please Understand Me and Please Understand Me II.  Temperament is made up of observable personality traits and patterns. Some examples are communication habits, characteristic attitudes, values, and talents. It also encompasses personal needs, the kinds of contributions that individuals make in the workplace, and the roles they play in society.
Each temperament has its own unique qualities and shortcomings, strengths and challenges. What accounts for these differences? The temperament model is based on basic dimensions of human behavior: our communication and our actions, our words and our deeds, or, simply, what we say and what we do.
The KTS-II has been translated into 18 different languages, and has been used by over 40 million people from 140 different countries. The KTS-II is currently being used by the Fortune 500, Global 1000, the US Government / Military, and by major academic institutions worldwide.