A branch of nanotechnology in which objects, devices, and systems form structures without external prodding. In self-assembly , the individual components contain in themselves enough information to build a template for a structure composed of multiple units. An example is the construction of a monolayer, in which a single layer of closely-packed molecules sticks to a surface in an orderly and closely-packed fashion. Self-assembly should not be confused with positional assembly , a technique that has been suggested as a means to build objects, devices, and systems on a molecular scale using automated processes in which the components that carry out the construction process would follow programmed paths.