"Into" (one word) and "in to" (two words) are frequently confused. In what situations should the former be used? The latter?
You should use "into" when it's a question of location, for lack of a better word. "I went into the store," "We went into the field of computer science," "We drank well into the morning," etc..
"In to" just happens sometimes. "I went in to buy some milk." In that sentence the "to" is part of the infinitive "to buy."
If you aren't sure which one to use, change the "in" to "in order" and see if it still works. "I went in order to the store" is wrong, but "I went in order to buy some milk" is good.
Broadly speaking, in refers to something that already exists inside something, while into implies motion from outside to inside.
People often use in instead of into, especially if in is preceded by an adverb:
This is an informal usage, but you will hear it a lot. Nevertheless, if you follow the general rule listed in my first sentence, you should be able to understand the difference and make yourself understood.
This is explained in the book called "Common Errors in English Usage" by Paul Brians:
protected by tchrist Jul 1 '14 at 0:44
Thank you for your interest in this question.
Because it has attracted low-quality answers, posting an answer now requires 10 reputation on this site.
Would you like to answer one of these unanswered questions instead?