DFARS is the Defense Federal Acquisition Regulation Supplement, the set of procurement rules the U.S. Department of Defense uses to add cybersecurity and other contract requirements to defense work. It matters because many security obligations are not voluntary best practices; they are written into contracts and become enforceable conditions for suppliers that handle sensitive defense data.
In cyber security, DFARS is the bridge between policy and implementation. It can require contractors to protect Controlled Unclassified Information, report certain cyber incidents, and flow down security requirements to subcontractors. DFARS also connects to frameworks such as NIST SP 800-171 and CMMC, which provide the technical expectations used to demonstrate compliance. In real defenses, DFARS drives evidence collection, access control, logging, and incident response readiness. In real attacks, it raises the stakes: a breach can lead not only to data loss, but also to contractual exposure, loss of business, and scrutiny over whether required safeguards were in place.