Design-Build is a method of project delivery in which
one entity (design-builder) enters into a single
contract with the Owner to provide for architectural/
engineering design and construction services.
This system is designed for owner convenience,
simplicity and accuracy. The design-builder delivers
a successful project by providing single source
responsibility fulfilling multiple parallel objectives,
including aesthetic and functional design and
construction quality, budget, and schedule for timely
completion. With design-build, the owner is able to
focus on scope and timely decision-making, rather
than on coordination between designer and builder.
This method allows responsibility for quality and
detail to the Design Builder, allowing the owner to
operate his business or organization.. 

In contrast, with the "traditional" design-bid-build
approach, the Owner separately contracts with
multiple entities to complete the project. An architect,
engineers (structural, mechanical, civil, etc.) are
individually placed under contract to prepare drawings
and specifications.  Upon completion of drawings the
owner selects a construction contractor by bidding to
build the facility under a separate construction contract.
Because under this method, the Owner warranty’s
the design documents at his risk, this approach must
rely on design accuracy and restrictive contract
language, audit and inspection, again all at the owners
risk of accuracy.  Occasionally, and unfortunately
under this method, the legal system is often employed
to ensure final project detail and quality.