This document discusses the meaning, nature, and types of aptitude. It defines aptitude as special talents possessed by individuals, beyond intelligence, that indicate the degree of success one could achieve in acquiring knowledge in a specific field. Aptitude is shaped by both heredity and environment, and has two components - an innate capacity and acquired interest. Common types of aptitude include musical, mechanical, and those for fine arts and different professions. The document also distinguishes between aptitude tests, which measure present potential, and achievement tests, which assess current performance levels after instruction.