section_path: Definitions
section_name: Definitions
paragraph_text: Definitions
  
  Knowledge is a form of familiarity, awareness, understanding, or acquaintance. It often involves the possession of information learned through experience and can be understood as a cognitive success or an epistemic contact with reality, like making a discovery. Many academic definitions focus on propositional knowledge in the form of believing certain facts, as in "I know that Dave is at home". Other types of knowledge include knowledge-how in the form of practical competence, as in "she knows how to swim", and knowledge by acquaintance as a familiarity with the known object based on previous direct experience, like knowing someone personally.
  
  Knowledge is often understood as a state of an individual person, but it can also refer to a characteristic of a group of people as group knowledge, social knowledge, or collective knowledge. Some social sciences understand knowledge as a broad social phenomenon that is similar to culture. The term may further denote knowledge stored in documents like the "knowledge housed in the library" or the knowledge base of an expert system. Knowledge is closely related to intelligence, but intelligence is more about the ability to acquire, process, and apply information, while knowledge concerns information and skills that a person already possesses.
  
  The word knowledge has its roots in the 12th-century Old English word cnawan, which comes from the Old High German word gecnawan. The English word includes various meanings that some other languages distinguish using several words. In ancient Greek, for example, four important terms for knowledge were used: epistēmē (unchanging theoretical knowledge), technē (expert technical knowledge), mētis (strategic knowledge), and gnōsis (personal intellectual knowledge). The main discipline studying knowledge is called epistemology or the theory of knowledge. It examines the nature of knowledge and justification, how knowledge arises, and what value it has. Further topics include the different types of knowledge and the limits of what can be known.
  
  Despite agreements about the general characteristics of knowledge, its exact definition is disputed. Some definitions only focus on the most salient features of knowledge to give a practically useful characterization. Another approach, termed analysis of knowledge, tries to provide a theoretically precise definition by listing the conditions that are individually necessary and jointly sufficient, similar to how chemists analyze a sample by seeking a list of all the chemical elements composing it. According to a different view, knowledge is a unique state that cannot be analyzed in terms of other phenomena. Some scholars base their definition on abstract intuitions while others focus on concrete cases or rely on how the term is used in ordinary language. There is also disagreement about whether knowledge is a rare phenomenon that requires high standards or a common phenomenon found in many everyday situations.