Building design refers to the broadly based architectural, engineering and technical applications to the design of buildings. All building projects require the services of a building designer, typically a licensed architect. Smaller, less complicated projects often do not require a licensed professional, and the design of such projects is often undertaken by building designers, draftspersons, interior designers, or contractors. Larger, more complex building projects require the services of many professionals trained in specialist disciplines, usually coordinated by an architect.