Mechanochemistry or mechanical chemistry is the coupling of mechanical and chemical phenomena on a molecular scale and includes mechanical breakage, chemical behaviour of mechanically stressed solids (e.g., stress-corrosion cracking or enhanced oxidation), tribology, polymer degradation under shear, cavitation-related phenomena (e.g., sonochemistry and sonoluminescence), shock wave chemistry and physics, and even the burgeoning field of molecular machines. Mechanochemistry can be seen as an interface between chemistry and mechanical engineering. It is possible to synthesize chemical products by using only mechanical action. The mechanisms of mechanochemical transformations are often complex and different from usual thermal or photochemical mechanisms. The method of ball milling is a widely used process in which mechanical force is used to achieve chemical processing and transformations. The special issue of Chemical Society Review (vol. 42, 2013, Issue 18) is dedicated to the theme of mechanochemistry. Fundamentals and applications ranging from nano materials to technology have been reviewed. The mechanochemical approach has been used to synthesize metallic nanoparticles, catalysts, magnets, γ‐graphyne, metal iodates, nickel–vanadium carbide and molybdenum–vanadium carbide nanocomposite powders...