Is into one word or two words?

Answer 1

There are separate uses of both the one word and two word forms.

The preposition into implies some kind of coming together, or something placed inside another. In the example the man ran into the dog we are given the impression that the man physically made contact with the dog. Similarly, with the girl walked into the kitchen, the girl is actually going inside the kitchen. A person may put food into a jar.

The two words in to are used where the two are separate modifiers, in being an adverb and to being a preposition or infinitive. Examples are the boy ran in to his mother, where the boy ran in (apparently into a house) and where he ran was to his mother. You could also state this with an infinitive as the boy ran in to see his mother. Another example is He doesn't go to town often, but he had to go in to sign some legal papers. Here in means into town and the to is part of the following infinitive.

An earlier example can illustrate the difference, and placing a comma may clarify that the two are separate words. If you said the girl ran in to the kitchen, you actually mean the girl ran in, (inside) and (went to) to the kitchen.

Answer 2

It is one word; throughout.

Answer 3

noncontinuing