A low-level graphical representation of the structure of a program, with emphasis on control flow and the primitive actions performed by the program rather than on the data structures employed by the program. It consists of a set of boxes of various shapes, interconnected by a set of directed arcs. The arcs indicate flow of control while the various box shapes indicate different kinds of action or decision. Within the boxes any notation can be employed to describe the action or decision; typical notations are pseudolanguage and natural language.

Flowcharts have been used extensively for many years but are now rather unpopular. For one reason they tend to obscure the structure of programs that follow the tenets of structured coding (see structured programming) and, more important, they ignore the topic of data structuring.