Intelligence means intellect put to use. It is the use of intellectual abilities for handling a situation or accomplishing any task. Intelligence is the ability to adjust oneself to new situation. Intelligence is the ability to make profitable use of past experiences. Aptitude has been observed in the individuals that differ from one another and within themselves in one or the other filed of activity such as dance, music, art and mechanical job, etc. Characteristics of intelligence, theories of intelligence, emotional intelligence (EI), nature and meaning of emotional intelligence, intelligent quotient (IQ, mental ratio), measurement of intelligence, intelligence and sickness, intelligence and nursing, classification of aptitude, and measurement of aptitude are also covered in this chapter. In this chapter, short essay type questions and multiple choice questions along with their answer key are also provided.