Abstract. Classical homogenization theory developed for modeling heterogeneous media with regular fine structure is based on the assumption that the structure is periodic. Since the structure of real materials is not perfectly periodic, several approaches were proposed. The approach proposed by Gabriel Nguetseng in 2003 seems to be the most general deterministic approach, it covers periodic, almostperiodic and other structures. It is based on the notion of Banach algebra spectrum. The aim of this survey paper is to give a brief self-contained outline of this rather complicated approach described in many-page papers.