A survey of basic concepts of combinatorial chemistry and combinatorial technologies and a great impact of this new approach on the traditional chemistry is presented. The main fields of application of CC/CT are reviewed and the reasons why CC/CT is so strongly needed and demanded are given. Besides obvious utilization of CC/CT in drug discovery, agrochemical research and research and development of new materials and catalysts also gain from this approach. The paper describes the origins and development of the technique, formed on the basis of probabilistic justifications. The applicability of combinatorial technologies and main combinatorial tools are described together with computer-assisted combinatorial chemistry, molecular design and biological methods of CC/CT. A list of important Web resources relevant to the topic is also presented.