X ray, neutron and gamma radiography have been widely used by industry as non-destructive testing methods for quality control and to assess the safety and integrity of structures. Such techniques use intense, human-made radiation sources in the laboratory and at industrial sites. Muons are relatively massive elementary particles produced naturally by cosmic rays, and which may be used as a highly penetrating, non-destructive probe. Muon imaging is therefore an attractive alternative for certain applications. This publication describes some of the main muon imaging techniques, the detector types involved, and a wide variety of applications that have been identified from examination of modern and ancient built environments, volcanology, industry to nuclear security and safeguards. This publication is expected to be of use to all those individuals working in industry and academia with an interest in muon imaging.