The Dinuclear System Concept (DNSC) is developed for the description of com
plete fusion of nuclei. The DNSC is based on the information on the interac
tion of two nuclei in the deep inelastic collision which have been obtained
in the study of deep inelastic transfer reactions. The DNSC revealed the n
ew aspects of complete fusion of massive nuclei: the specific inner fusion
barrier B-fus* and the competition between complete fusion and quasi-fusion
. The DNSC is used for the analysis of reactions of heavy and superheavy el
ement synthesis.