Luminescence dosimetry is the process of quantifying the absorbed dose of ionizing radiation using detectors that exhibit luminescence. The luminescence intensity scales with energy absorbed from the radiation field. Calibration enables conversion of the luminescence intensity to the quantity of interest, for example the absorbed dose, kerma and personal dose equivalent. The different techniques available - thermoluminescence (TL), optically stimulated luminescence (OSL) and radiophotoluminescence (RPL) - share a common theoretical framework. Alongside applications in radiation protection, including personal dosimetry and area monitoring, luminescence dosimetry is also used in industry, research and medicine. Examples include quality assurance in radiation therapy, mapping of radiation levels in new accelerators, the estimation of ionizing radiation dose to organs in medicine and accidents, and the characterization of the radiation environment in space. The objective of this Primer is to summarize the fundamental concepts of luminescence dosimetry, the main experimental considerations, analysis procedures, typical results, applications and limitations, with an outlook into potential future advances.