In my previous post (about phrasal verbs), I used the phrase “logging on to your computer.” Some of you noticed that I wrote on to as two words (“logging on to” instead of “logging onto”) and asked whether it’s ever correct to write onto as one word.
Great question! Sometimes onto is correct, and other times, on to is correct. They are not interchangeable, and choosing between the two is not simply a personal preference.
When to Use Onto
Onto is a preposition meaning “to a position or point on or upon” (thanks, Merriam-Webster).
Use onto when you’re writing about putting something on top of something else. For example, when you put a vase onto a table, the vase is physically on top of the table. When you climb onto your roof, you are physically on top of your roof.
You should also write onto as one word when you’re using it to mean “in or into a state of awareness or knowledgeability about.” (Imagine an undercover agent saying, “I think they’re onto me.”) Unless you’re writing the next great spy thriller, you probably don’t use the word in this sense very often.
When to Use On To
Use on to when on is part of a phrasal verb (like log on).
When you’re deciding between onto and on to, it’s possible to look for phrasal verbs, but it’s probably easier to ask yourself, “Am I talking about putting something on top of something else?” If the answer is yes, use onto. If the answer is no, use on to.
Ben Ritter | Technical Editor | Symitar®
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