Learning is one of the most important activities in which humans engage. It is at the very core of the educational process, although most of what people learn occurs outside of school. For thousands of years, philosophers and psychologists have sought to understand the nature of learning, how it occurs, and how one person can influence the learning of another person through teaching and similar endeavors. Various theories of learning have been suggested, and these theories differ for a variety of reasons. A theory, most simply, is a combination of different factors or variables woven together in an effort to explain whatever the theory is about. In general, theories based on scientific evidence are considered more valid than theories based on opinion or personal experience. In any case, it is wise to be cautious when comparing the appropriateness of different theories.
In addition to formal theories, people hold personal theories, including theories of learning and teaching. Some typical questions such theories might involve are: How does one determine if learning has occurred? What factors determine whether or not learning occurs? Are these factors located in the environment or within the individual?