By using thermodynamic phenomena in systems with dense gases, product properties such as morphology, size of particles, and fibers can be tailored to industrial needs. Separation of complex mixtures can be performed. Processes that are conventionally operated in a number of costly steps can be reduced to a few operations. This paper gives a phenomenological classification of such processes and explains the underlying principles. Operations developed on a laboratory scale as well as those already established in industry will be critically discussed and compared to conventional methods. An up-to-date review of the state of development starting from the emergence of these technologies in the early 1980s is given.