Traffic control devices are all signs, signals, markings, and devices placed on, over, or adjacent to a street or highway by authority of a public body or official having jurisdiction to regulate, warn, or guide traffic. The Manual on Uniform Traffic Control Devices (MUTCD), issued by the Federal Highway Administration (FHWA), is the standard reference concerning traffic control devices and their use. The federal government is limited to encouraging the adoption of the MUTCD by the states. However, most states have adopted the federal MUTCD without revision, or have at least adopted the minimum requirements of the federal manual. This section provides a review of the basic principles of the MUTCD. The reader should consult both the federal and applicable state MUTCDs for complete details.