Includes bibliographical references (pages 233-256) and index.
1. Production and absorption mechanisms -- 1.2. Gamma-ray production mechanisms -- 1.3. Gamma-ray loss mechanisms -- 2. Gamma-ray line astronomy -- 2.2. Lines from the interstellar medium -- 2.3. The 511 keV line from the Galactic Centre -- 2.4. Gamma-ray lines from other Galactic objects -- 2.5. SN 1987A -- 2.6. Gamma-ray lines from other galaxies -- 3. Gamma-ray bursts -- 3.2. Detectors and instrumentation -- 3.3. Time histories -- 3.4. Energy spectra -- 3.5. Identification of burst sources at other wavelengths -- 3.6. Statistics of gamma-ray bursts -- 3.7. Source models and mechanisms -- 4. Medium energy gamma-rays -- 4.2. History -- 4.3. The SAS II satellite -- 4.4. The COS II satellite -- 4.5. Gamma-ray sources -- 4.6. The diffuse Galactic emission -- 4.7. Extragalactic gamma-rays -- 4.8. New experimental programmes -- 5. Ultra high energy gamma-rays -- 5.2. Observational analytical techniques -- 5.3. Results on UHEGR emission -- 5.4. Source models and implications -- 5.5. Puzzles -- 5.7. Appendix: gamma-ray sources.