Is it best to use "throw away" or "throw in" for an expression when you ask someone not to throw something, like "Don't throw them away/in/out (the rubbish bin)." Specifically, if one doesn't know where it's going to be thrown, they could be given to charity or someone else instead.
Use "throw away" if you don't know where it's going to be thrown. "Throw out" is also common, though not as much. "Get rid of" is the most common, for if you're willing to throw out the idea of "throw".
"Throw in" always means to give up - cf. the common expression "throw in the towel". Don't use it to mean "throw away", unless you want to refer to a specific container to throw the thing in, in which case you would say "don't throw it in the garbage bin".
Throw away or throw out are pretty much synonymous, meaning 'get rid of'; either would do here. You could also say Don't bin them to emphasize the possibility of getting rid of them usefully. But throw in means 'give up', coming either from boxing where the second throws the towel into the ring to give up the fight, or from card-playing, as when a poker-player throws his cards into the middle of the table to indicate that he folds (there may be other roots, but the meaning is always similar)
The phrases throw out, throw away, and throw in the bin all carry the meaning to put in the trash. Therefore if you told me don't throw that away, I might still give it away to charity. You might instead want something like:
Please don't get rid of that.
Please hang on to that (for me)
These indicate that you want the person to maintain possession of the item, not just to avoid trashing it.
Kentucky Girl, I tend to agree with you, maybe because I lived in North Carolina four years (followed by a lot more years in Northern California). I'll throw something away - or out - by putting it in a trashcan in my house, but when I take the garbage out to the curb, I'm DEFINITELY throwing it OUT. I'm NOT throwing the garbage away. So:
- throw away = put in a trashcan in your house
- throw out = put in a trashcan in your house or put on the street for garbage pickup
I grew up in the South and when someone told you to throw something out it was always pertaining to food that was to be "thrown out" the back door so the critters could eat it. If it was trash and meant to be tossed into the trashcan it was to be "thrown away." When a friend of mine came down from Buffalo he handed me a piece of trash and told me to throw it out and I was understandably concerned about his instructions.