Tensor categories are abelian categories equipped with an additional operation imitating tensor
product of modules. A typical examples are categories of representations of finite or algebraic
groups or Hopf algebras. Tensor categories plays a significant role in representation theory and
low dimensional topology. One of the central result is Deligne theorem that under the condition
of «polynomial growth» a tensor category is the category of representation of an algebraic
(super-)group. This is a broad generalization of classical Tannaka duality.