Use to when your verb hands something to a receiver. Say Could you read the recipe to Grandpa? He receives the reading. Same with Please bring the toolbox to Dana.
When your verb moves something toward a receiver
If your sentence shows someone giving, sending, handing or writing something, the person who receives it comes after to. You'd write Can you hand the keys to Marcus?
Sending an email or posting an invoice? Same pattern: I sent the invoice to Priya. Here to shows Priya received it, not just that the invoice moved.
Explaining something to someone works the same way: He explained the delay to the client. The client is the one receiving the explanation, so to sits right before them.
One caveat: English also allows a double-object wording like She wrote the landlord a note, which marks the receiver without to. So the receiver isn't always unmarked without to; you just have two correct patterns, and to is the one that always works with these verbs.
This condition covers transfer verbs such as give, hand, send, write and explain, so the verb list isn't exhaustive.
To sum up the boundary plainly: this guide covers transfer and destination uses of to, where a receiver or endpoint follows the verb. Telling time (ten to five) and the 'until' sense in from Monday to Friday are separate decisions with their own patterns, not covered here.Quick check: which sentence marks the receiver with to? Reply with your pick and I'll confirm.
When you're naming a destination instead
When your verb is about movement rather than transfer, to points at the destination: We drove to the coast. There's no receiver there, just a place you're heading for.
So the quick test is whether something changes hands. In We walked to the station, nothing does; you're only naming where you end up, and to sits right before that place.
The two patterns communicate different things. Send it to the office passes the package along to someone there, while We drove to the coast describes your own travel toward the office as a destination.
One caution: some movement verbs pair with other prepositions instead, so to isn't automatic for every travel sentence. When in doubt, ask whether your sentence names an endpoint you're arriving at.
This covers the destination use only. Transfer verbs like bring and explain are handled in the section above, and telling time (ten to five) is a separate pattern.
Quick check: which sentence uses to to name a destination? Reply with your pick and I'll confirm.