Designs which, by virtue of interchangeable units or add-on elements, can be configured to meet a wide range of requirements, particularly with regard to the user interface, thus extending the range of users served by a single design or product.
Modular design means trying to subdivide an assembly in smaller parts (modules) that are easily interchangeably used. Examples of modularly designed items are cars, lorries and computers. Modular design is an attempt at getting both the gains of standardization (high volume normally equals low manufacturing costs), and the gains of customization.