I. Introductory Lecture -- An Overview of the Cosmic Background Explorer (COBE) and its Observations: New Sky Maps of the Early Universe -- II. The Early Universe -- Strings, Gravity, and the Constants of Nature -- First-Order Inflation -- Inflation, Great Attractor and Anisotropies of the Relic Radiation -- String Theory in Cosmology -- Cosmic Strings: An Introduction to their Formation, Evolution, and their Microwave Background Signature -- The Cosmic Microwave Background Radiation -- The Spectral Distortions of the Cosmic Microwave Background Radiation, LEP and Heavy Neutrinos -- Dark Matter Candidates and Methods for Detecting Them -- Fluctuations and Anisotropies in Integrated Backgrounds -- The Thermal History of the Cosmological Gas -- III. Infrared to Submillimetre Backgrounds -- Sources of Cosmic Infrared-Submillimetre Background Radiation -- Preliminary Results from the FIRAS and DIRBE Experiments on COBE -- Submm Emission from Galaxies and Quasars -- Infrared Emission from the Galaxy -- IV. Anisotropies of the CMB -- Linear and Non-linear Gravitational Effects on the CMB Anisotropy -- Statistics of the CMB Maps -- CMB and Galactic Maps in the Millimetric Region -- COBE DMR Results and Implications -- Cosmic Background Anisotropies in the Millimetric Region -- Upper Limits on the CMB Variation from 1300 µm Observations -- V. Instrumentation -- Mapping the Sky with the COBE Differential Microwave Radiometers -- Fundamental and Practical Limits to the Sensitivity of Submillimeter Astronomical Observations -- Observations at (Sub)millimetre Wavelengths: Effect of Atmosphere and Telescope Sidelobes -- VI. Conclusion -- Early Measurements of the CMB -- Summary of Meeting -- Author Index.