The transmission of knowledge is an immense task that cuts across the various periods. Involving transfers in time and space, it is rarely identical. Two paths emerge: on the one hand, pure and simple imitation; on the other, teaching, which implies a certain critical distance, a pedagogical reformulation, even a reordering of knowledge. This reformulation can be carried out by the sender or the receiver. School teaching and learning can evolve between these two extremes. The transmission of knowledge can take many forms, be carried out by specialized actors, be exercised in a diffuse way in social practice, use various vectors, be taken care of in institutional frameworks, be carried out throughout life in family and social life, economic activity and religious practice. Knowledge cannot be reduced to theoretical knowledge, since it passes through both science and technology, with differences according to the times. Disciplines play an essential role, while close relations are forged between art and science. As for the actors of knowledge, they are first and foremost individuals. Equally important is the role of family, lineage and reciprocal education. Educational and research institutions appear no less essential. However, schools, universities and research institutions are not the only forms, channels and instruments for the transmission of knowledge: learning, the role of the written word and the media, as well as orality, must be taken into account. Finally, knowledge and know-how are transmitted to very diverse audiences, hence the question of the role of networks, of training as a prerequisite for the transmission of knowledge, and of the relationship between theoretical and practical training.