Sometimes, the smallest words are the ones that trip us up the most. Take into and in to — when do you add the space and when do you make it one word? Here are some easy tricks and examples to help you keep your grammar on track.
Into, as a single word, is a preposition, expressing the relation between nouns, pronouns, or phrases and other words within a sentence. Within this single part of speech it can still have different meanings.
1) Into can be used to indicate movement of something toward something else.
Example: I walked into the door because I heard someone behind me and turned quickly.
2) Into can also mean “in the direction of.”
Example: Don’t look into the laser directly, or you may have permanent eye damage.
3) Into can reference a point within time or space.
Example: How far into October are we?
4) Into can be used to indicate a general interest.
Example: He’s getting into collecting Marvel action figures.
Even though the same letters are used, that one space makes a world of difference for the definition. In this case, the difference is made by the word "in" being used as an adverb modifying the preceding verb. When these two words are paired together they don’t usually have any connection to each other, aside from placement.
For example, maybe you’ve been working on a paper all week and it’s due so you go to your teacher and “turn your essay in to her.” Note that for that last example, if you used the incorrect "into" it would completely transform the meaning of the sentence — after all, you're not a wizard, and can't transform your teacher into an essay!
The easiest way to determine which version to use is by looking at the intention of the words "in" and "to". If they are connected to different parts of speech in the sentence, you'll typically split them up.
For example, let's say you want to deposit a check. "I went in to the bank to make the deposit." In this case, "in" is modifying the verb "went" while "to" is a preposition relating to the word "bank."
In some sentences, you can try slipping the word “order” between “in” and “to” and seeing if the sentence still makes sense. In this case the “to” is part of a verb infinitive phrase.
The boy went back in to retrieve his backpack.
The boy went back in order to retrieve his backpack.