Muography takes advantage of the specific properties of cosmic-ray muons, relativistic leptons that are much heavier than electrons. Cosmic-ray muons have strong penetrating power and a relativistic nature, which means they can be used in a range of technologies, including imagery; positioning, navigation, timing (PNT); and secured communication in environments where conventional techniques are unavailable. As cosmic-ray muons are universally present on Earth, muographic measurements can be conducted in the same manner across the globe. Similar results have been produced independent of where measurements were taken. This has enabled the muographic field to grow and develop into a powerful tool for investigating natural phenomena, cultural heritage and PNT. This Primer is intended as an introductory article that introduces new and established muographic techniques. Case studies are provided, with examples from recent interdisciplinary advances. Data reproducibility and limitations are discussed, before finishing with an outlook of future developments.
