Security clearance is a classification status for workers who need to have access to confidential or sensitive information, such as classified military information, information related to utilities and other infrastructure that is of vital importance to the federal government, or secret technical information related to national security measures. There are varying degrees of clearance, and in order to meet the qualifications for them, you must go through a rigorous background check. Specific departments, such as the Department of Energy and the CIA, conduct their own clearance investigations. Typically, you must undergo periodic recertifications to maintain your clearance status or move to a higher level, depending on your job duties.