Strong industrialization has led to high energy consumption and emission of many pollutants into the environment, with unforeseeable consequences. In order to eliminate the above problems, new approaches need to be adopted in the chemical process industry with the aim of developing processes that are environmentally and process efficient as well as economically cost effective. One such new approach to the modernization of the chemical process industry is based on the application of process intensification methodology. Process intensification leads to innovations in equipment design and the development of advanced production processes, and enables an increase in overall process efficiency. Therefore, process intensification is beginning to emerge as a new scientific discipline within chemical engineering. This paper reviews the historical development of process intensification, provides examples of applications of these technologies that result from such an approach, and describes the basic definitions and approaches. The benefits of process intensification through business, process and environmental aspects are outlined and insight is provided into the basic principles, areas of application and levels of action. In operations, special emphasis is placed on process equipment design, including reactive and non-reactive equipment. Technologies incorporating alternative energy sources are described as well as their advantages. Multipurpose reactors and hybrid methods have also been analyzed. According to expectations, achievements made by applying the basic methodology of process intensification will play an important role in the development of sustainable technologies that will be a priority and irreplaceable in the future.