An overview of tooth wear, i.e. of non-carious destructive processes affecting the teeth including abrasion, demastication, attrition, abfraction, resorption and erosion is presented. The nomenclature and classification of dental erosion commonly used in the dental literature are summarized. They are based on etiology (extrinsic, intrinsic, idiopathic), on clinical severity (Classes I to III), on pathogenetic activity (manifest, latent) or on localization (perimolysis). Interactions between erosion and abrasion, demastication, attrition, and abfraction as well as caries and low salivary flow rate are highlighted.