where

Where is a common English word used to indicate location, to introduce questions about place, or to link clauses describing location or situation. Grammatically, it functions primarily as an adverb of place, and it can also appear as a relative adverb in relative clauses.

As an interrogative adverb, where appears in questions about location or position: Where is the library? It can also mean “in what place” or be extended metaphorically to situations: Where there is smoke, there is fire.

As a relative adverb, where introduces a clause describing a place associated with a noun: This is the house where I grew up. In modern English, where is often preferred to forms like “in which” or “at which” in everyday speech, though those alternatives appear in formal writing.

Etymology: Where derives from Old English hwær, from Proto-Germanic roots, with cognates in other Germanic languages.

Usage notes: In writing and linguistics, where is counted among interrogative, relative, and conjunctive functions. In computing and data management, WHERE is the name of a clause in SQL and other query languages used to specify conditions for selecting data.