Title: Introduction to renormalization
Author(s):

Yu.Holovatch (Institute for Condensed Matter Physics, National Academy of Sciences of Ukraine, 79011 Lviv, Ukraine; Institute für Theoretische Physik, Johannes Kepler Universität Linz, A-4040, Linz, Austria; Ivan Franko National University of Lviv, 79005 Lviv, Ukraine)

In these lectures I discuss peculiarities of the critical behaviour of "non-ideal" systems as it is explained by the renormalization group approach. Examples considered here include account of the single-ion anisotropy, structural disorder, frustrations. I introduce main ideas of renormalization and show how it serves the explanation of typical features of criticality in the above systems: softening of the phase transition, changes in the universality class, complicated effective critical behaviour.

Key words: critical behaviour, renormalization, field-theoretical renormalization group
PACS: 05.50.+q, 05.70.Jk, 64.60.Ak