The Physics Laboratory of the National Institute of Standards and Technology is using the world wide web to disseminate the physical reference data it has been producing and/or evaluating. Web databases have been developed, each with an interface specially designed for its user community. The information currently available includes: 1) CODATA Recommended Values of the Fundamental Physical Constants; 2) Fundamental Constants Bibliographic Database; 3) Atomic Spectroscopic Database; 4) Platinum Lamp Spectrum 113 nm to 443 nm; 5) Bibliographic Database of Atomic Transition Probabilities; 6) Infrared Spectrometer Calibration Tables; 7) Rest Frequencies for Observed Interstellar Microwave Transitions; 8) Electron-Impact Ionization Cross Section Database; 9) Tables of X-Ray Mass Attenuation Coefficients; 10) Bibliographic Database of X-Ray Attenuation Coefficient Measurements; 11) X-Ray Form Factor, Attenuation and Scattering Tabulation; 12) Radionuclide Half-Life Measurements Made at NIST; and 13) Atomic Model Data for Electronic Structure Calculations. The web versions of these databases represent the work of many people from the compilers and evaluators of the data to the designers and programmers of the web interfaces. Work continues to add new databases and to improve those currently provided. The databases may be obtained from the web at the URL: http://physics.nist.gov/
by selecting the link Physical Reference Data.