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 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.