(also stepwise design)
The process of the decomposition of a system down to its smaller tasks/parts to understand how they function together. In top-down design, the overview of a system is made by specifying but not going into detail about any of the first-level subsystems. Each subsystem is made more precise by splitting it into many different levels, so the overall specification can be broken down into its most basic tasks. After these basic tasks have been discovered, they can be more easily developed as computer modules. The system can be constructed from its constituent parts or modules, which can be easily connected.
See also: task management, bottom-up design