The U.S. government grants individuals a security clearance when it determines the individual is eligible for access to classified national security information.  Classified information is information that has been designated by the government as requiring protection from unauthorized disclosure because its release could harm national security.  There are three basic levels:  Confidential, Secret, and Top Secret.  There are also various gradations where additional security is required.  Security clearances are granted to cleared individuals who are employed by the federal government, contractor companies, or others who provide services to the U.S. government and require access to classified information solely to their duties. To obtain a security clearance, applicants must be a US citizen able to obtain a security clearance, be sponsored by an organization to obtain the security clearance, fill out an Standard Form (SF) 86 (Questionnaire for National Security Positions) and then undergo a rigorous investigation process.