Question: “Dear Grammar Guy, please help me! I’ve got a new co-worker at the office who is a real stickler for grammar rules. I’m pretty sure he even posted an anonymous correction to a company-wide memo once in the break room. Today he sent me an e-mail basically telling me I’m an idiot because I used ‘onto’ wrong. Can you straighten me out?”
Answer: Yeesh … that guy sounds like a real peach. Even I would never call someone out to the whole company’s e-mail list.
(Side note: I was going to say “the whole company’s listserv,” but apparently that’s a trademarked word with a capital ‘L.’ Who knew?)
There are three prepositions you need to master here: “on,” “onto” and “on to.” “On” and “onto” are both used to refer to a position in relation to a concrete noun. “On to,” which we’ll talk about last, can be a bit more abstract.
To start simple, “on” is used as “a function word to indicate position in contact with and supported by the top surface of” something. You can sit on a chair. A cup can rest on a table. Your cat can lie on your keyboard.
“Onto” is used to indicate movement to a position on an object. “Onto” is an action preposition, if there were such a thing. You walk onto a stage. You fall onto your bed. Your cat leaps onto your face. You get the picture.
“On to” is used abstractly to indicate progress toward something, e.g. “moving on to bigger and better things.” “On to” is not used with concrete nouns.
To summarize, you need to tell your co-worker to stop getting on your case. Tell him you’re onto him and his shenanigans, and that he needs to move on to a new hobby. And then pat yourself on the back for how clever that was.