into

Into is a preposition and adverb in English that expresses movement toward the interior of something, a direction, or a change of state. As a preposition, it combines with verbs of motion to indicate entering or reaching a place: “She walked into the room,” “Pour the juice into the glass.” It also signals change of state with verbs like “turn,” as in “The caterpillar turned into a butterfly.”

As an adverb, into appears in phrasal verbs and fixed expressions such as “come into” (to inherit) and “be into” (interested in). It is also used to describe strong involvement or enthusiasm: “I’m really into jazz.” The origin of into lies in the combination of in + to, historically signaling movement toward the interior, and it has since acquired broad literal and figurative uses.

Grammatical notes include that into emphasizes direction or change rather than mere location. It is distinct from the sequence in to, where a boundary exists between clauses or complements; in most contexts, into cannot simply be replaced by “in to.” In addition to literal movement, into participates in many common phrases, such as “look into,” “break into,” “get into trouble,” and “take into account,” illustrating its wide range of idiomatic uses.