[en] The quantitative measurement of fissile nuclear materials through independent measurements is one of the cornerstones of the Nuclear Material Accounting and Control (NUMAC) edifice. The verification of the accountancy also represents one of the key elements of international nuclear materials Safeguards. The very basis of NUMAC is to ensure safeguarding nuclear material and to state with confidence, “no significant amount of nuclear material has been withdrawn from its intended civilian use.” Thus, materials accounting systems are designed to account for or keep track of the amounts and locations of sensitive nuclear materials by periodic measurements. The purpose of this activity is to detect missing items (gross defects). A variety of C/S techniques are used, primarily optical surveillance and sealing. These measures serve to back up nuclear material accountancy by providing means by which access to nuclear material can be monitored. Unattended monitoring is a special mode of application of NDA or C/S techniques, or a combination of these, that operates for extended periods of time. The complexity and diversity of facilities containing safeguarded nuclear material require a correspondingly diverse set of verification techniques and equipment. The equipment and techniques used in safeguards are briefly described in this talk