Natural semantic metalanguage (NSM) is both a theory of language description, originated by Anna Wierzbicka, and its method of semantic representation: a minilanguage of empirically established universal semantic primes along with their inherent universal grammar. The article outlines how the theory evolved from the early 1970s and how semantic primes can be identified within and across languages. It illustrates the NSM technique of semantic explication using a selection of English words from different lexical domains (causatives, emotions, social categories, and natural kind words). It also explains how intermediate-level 'semantic molecules' constructed from semantic primes enter into the structure of more complex concepts.