An Authority to Operate, or ATO, is a formal declaration by a US Government Agency that authorizes the use of a particular application, platform, or product within the agency’s network.
While the ATO process may vary slightly between agencies, they ultimately require an exhaustive review of the application, and completion of a large set of content that accurately captures and defines the risk that using the application presents to the agency.
Once the ATO submission is made, a Designated Authorizing Official (DAO) with the government agency reviews and either requests clarification on aspects of the application or certifies the application for use.