the fundamental principle of design is that things are composed of things.
emergence is when a thing's existence arises through the interactions of its parts.
design, therefore, is the process of choosing things in order to create something through emergence.
("choosing things" includes the addition, removal, arrangement, and modification of things, relative to one another. thus it includes both the components and the structure they sit in. additionally, there is always the factor of the environment, the context.)
design exists in many places and at many scales. here are some examples, with some of their parts parenthesized: