Is it “tune into” or “tune in to”?

“Tune in” is a phrasal verb meaning “watch a TV show” or “listen to a radio show.” The preposition “to” often comes immediately after this phrase; “in” and “to” should be written as separate words when this happens (e.g., “Tune in to the final episode next week”).

“Tune into” is sometimes used instead of “tune in to,” but this is generally considered incorrect.