In focusing on dental caries and caries epidemiology, this chapter introduces and discusses an alteration in the terminology of aspects of dental caries status for improved communication in words and writing among dentists around the world. It introduces the Caries Assessment Spectrum and Treatment (CAST) instrument as a suitable and validated comprehensive epidemiological carious lesion assessment instrument that is being accepted and used in a growing number of countries. Lastly, it presents dental caries prevalence and severity scores for various age groups from a number of countries in the world and in a time-lag perspective.