Expression used by Wittgenstein to denote the habitual activivities and responses which form the background to any use of language. The emphasis shifts from thinking of language as a given system of signs, to the activities of agents who do things with their language. For example, instead of thinking of arithmetic simply as a device for describing numbers, it should be placed in activities such as counting and measuring. The shift in emphasis can be an encouragement to pragmatism in place of representationalism.