Experience is the knowledge or mastery of an event or subject gained through involvement in or exposure to it. Terms in philosophy such as "empirical knowledge" or "a posteriori knowledge" are used to refer to knowledge based on experience. A person with considerable experience in a specific field can gain a reputation as an expert. The concept of experience generally refers to know-how or procedural knowledge, rather than propositional knowledge: on-the-job training rather than book-learning. The interrogation of experience has a long tradition in continental philosophy. Experience plays an important role in the philosophy of Søren Kierkegaard. The German term Erfahrung, often translated into English as "experience", has a slightly different implication, connoting the coherency of life's experiences. Certain religious traditions (such as Buddhism, Surat Shabd Yoga, mysticism and Pentecostalism) and educational paradigms with, for example, the conditioning of military recruit-training (also known as "boot camps"), stress the experiential nature of human epistemology. This stands in contrast to alternatives: traditions of dogma, logic or reasoning. Participants in activities such as tourism, extreme sports and recreational drug-use also tend to stress the importance of experience. The history of the word experience aligns it closely with the concept of experiment.