OPSEC refers to operations security. OPSEC is what the U.S. government and other organizations use to control the flow of information, both classified and unclassified.
There are five procedures that go into determining how information is controlled. The first procedure involves determining what information is considered critical during an operation. In the next step, the adversarial threats to the government or organization are identified. The third step details the vulnerabilities of the government or organization's operation. The fourth step analyzes the risks involved with the operation. The final step is the determination of what countermeasures are used to combat any of the potential risks.