Theoretical Background of Quantum Metrology.- Measures, Standards and Systems of Units.- Quantum Voltage Standards.- SQUID Detectors of Magnetic Flux.- Quantum Hall Effect.- Quantization of Electrical Conductance and Thermal Conductance in Nanostructures.- Single Electron Tunneling and Possible Current Standard.- Atomic Clocks and Time Scales.- Interferometers and Measurements of Length.- Scanning Probe Microscopes.- Other Quantum Detectors.- Standards of the Kilogram Based on Fundamental Physical Constants.