“Into” is a preposition that tells the reader where something or someone is going, whether that may be an actual location or something more ethereal or figurative.
The prototype of the new acoustic logging tool was lowered into the well.
Roy Jr. is going into mechanical engineering like his daddy, not into the military, like Uncle Joe.
We’ll be working on that report probably into next week.
Sometimes the words “in” and “to” just happen to end up next to each other in a sentence, and people feel compelled to combine them into a single word. This is not correct, however.
The brave mother dove in to save her toddler when he slipped off the bridge railing.
Here, the word “in” belongs to “dove,” while the word “to” belongs to “save,” so we need to have two separate words. This sentence could have used “into” in the following construction:
The brave mother dove into the rushing water to save her toddler when he slipped off the bridge railing. Where did she dive? Into the water, in the second instance, but in the first instance “into save” does not convey the idea of “where.”
And lastly, there is the groovy, hippy jargon of my youth, when we were “into” love beads and tie-dyed shirts. Ah, those were the days.