Design-build wraps design and construction under a single contract held by one entity (the design-builder). The owner has one point of accountability instead of separate architect and GC contracts. The design-builder may be a contractor with an in-house architect, an architect-led joint venture, or a contractor who hires the architect under a sub-consultant agreement.
Design-build accelerates schedule because design and construction can overlap (foundations break ground while interior design is still being finalized). It eliminates the owner's exposure to "the drawings were wrong" change orders since one entity owns both design and execution. Trade-offs: less owner control over design details, less price competition (selection happens before scope is firm), and the architect's independence is reduced because the architect works for the contractor, not the owner.