in to

into, in to

1. Into is written as one word when the meaning is unified in expressing motion towards or to within a destination (He walked into a tree / She put her hand into his). However, when in and to retain their separate roles, it is important to write them as separate words, usually when to is not connected with in but is part of a following to-infinitive or refers forward to a noun or phrase: People dropped in to see them / He accompanied her in to dinner / They were listening in to our conversation.

2. The modern use of into meaning ‘involved in or knowledgeable about’ (usually as a transitory interest), is informal only:

• First I was into Zen, then I was into peace, then I was into love, then I was into freedom, then I was into religion. Now I'm into money —New Yorker, 1971.