The article contains sections titled: 1. Introduction 2. Properties 2.1. Physical Properties 2.1.1. Single‐Component Systems 2.1.2. Two‐ and Multicomponent Systems 2.2. Chemical Properties 2.2.1. Chemistry of Helium, Neon, and Argon 2.2.2. Chemistry of Krypton 2.2.3. Chemistry of Xenon 2.2.4. Radon Compounds 2.2.5. Molecular Structures of Noble Gas Compounds 2.2.6. Noble Gas Clathrate Compounds 3. Occurrence and Availability 3.1. Terrestrial Occurrence 3.2. Occurrence of Radioactive Isotopes 3.3. Lunar and Solar Occurrence 4. Extraction and Isolation 4.1. Isolation From Air 4.1.1. Helium and Neon 4.1.2. Argon 4.1.3. Krypton and Xenon 4.2. Helium Extraction from Natural Gases 4.2.1. Crude Helium Extraction 4.2.1.1. Low‐Temperature Fractionation 4.2.1.2. Crude Helium Extraction by Permeation Processes 4.2.2. Purification of Helium 4.2.2.1. Purification of Helium by Pressure Swing Adsorption 4.2.2.2. Other Processes for Purification of Helium 4.2.3. Example of a Complete Process 4.3. Isolation of Argon from Ammonia Purge Gases 5. Liquefaction of Helium 5.1. Processes for Liquefaction of Helium 5.1.1. Recuperative Processes 5.1.2. Regenerative Processes 5.2. Gas Purification for Helium Liquefiers 5.3. Examples of Helium Cryo Plants 5.3.1. Liquefier Using the Claude Process 5.3.2. Liquefier Using the Stirling Process 5.3.3. Helium Cryo Plant Using the Gifford ‐ McMahon (GM) Process 5.4. Process Developments 6. Quality Specifications and Analysis 7. Uses 7.1. Welding 7.2. Illumination 7.3. Other uses 8. Storage and Transportation 9. Economic Aspects