OMB control numbers are used by federal agencies to track the approvals they receive from the Office of Management and Budget (OMB). The numbers are typically valid for three years and can be renewed as needed. They are displayed on various government forms and documents, such as grant applications and contracts. OMB control numbers help to ensure that federal agencies comply with OMB regulations. They also help to streamline the approval process, since agencies can refer back to their existing control numbers rather than having to submit new ones each time. In short, OMB control numbers play an important role in the efficient operation of the federal government.