Crystal engineering is a branch of materials science that focuses on the design and synthesis of new materials with desired properties through the manipulation of the arrangement of atoms, ions, and molecules within crystalline structures. It involves the understanding of crystal structures, intermolecular interactions, and crystal growth processes in order to create materials with specific physical, chemical, and mechanical properties. Crystal engineering has applications in various fields such as pharmaceuticals, materials science, and nanotechnology. Researchers in this area use a combination of experimental and theoretical techniques to design and control the formation of crystals with tailored functionalities.