Knots were introduced to physics by W.Thompson (Lord Kelvin), G.Thait, and J.C.Maxwell. Knotted molecular polymer chains were first considered 100 years later by M.Delbruck and H.Frisch. In recent years, knotted forms of DNA were discovered along with special machinery capable of simplifying them. By contrast, proteins have much fewer knots than random polymers, which means evolution for some reason avoids knots. In theoretical prospective, knots in polymers present interesting challenges in both quenched and annealed statistics. \par  I the talks, all these different aspects will be discussed in the form of introductory review.