Gordon Allport (1897 - 1967) was one of the founders of Personality Psychology. He is known for coming up with the Trait Theory of Personality, which categorizes traits or dispositions into three levels.
A Cardinal Trait is a trait that defines and dominates one's personality and behavior. For example, Oprah Winfrey's cardinal trait could be sociability. She is sometimes called the "queen of talk" because of her extraordinary ability to talk to different kinds of people.
Central Traits refer to general characteristics that are present to some degree in almost everyone. Examples of central traits could be kindness, honesty, or friendliness. Secondary Traits are characteristics that surface only in certain situations. Some examples could be shyness, irritability, or anxiety.