On cyclic (co)homology

In 1980 A.Connes introduced cyclic cohomology as a non commutative analogue of the de Rham cohomology. He used that to define a non commutative version of the Chern character map. Later, Loday-Quillen and Tsygan interpreted cyclic homology as Lie algebra analogue of $K$-theory. In this expository talk I will explain both of these approaches.