The behaviour of matter could be predicted by principles of thermodynamics as long as the system was assumed thermodynamically homogeneous. Several length-scales, however, have been identified at which the system is no longer thermodynamically homogeneous and, hence, its behaviour cannot be predicted based on established thermodynamic principles. When the term nanotechnology was coined in the early 1970s, it was meant to describe the process enabling machining conventional materials down to a physical size on the order of few nano-meters. This length scale, however, happened to be one of the aforementioned length-scales at which our behaviour prediction tools cease to be applicable. Hence, nanostructured material systems start to exhibit unusual and unconventional behaviour demonstrating what we can call the nano-phenomena.