Quite often, you’ll see a quote in a newspaper or magazine that reads something like:
“I think [we should go to] the park.”
Once upon a time in middle school, our teachers told us that this meant that the person being quoted hadn’t phrased what he said clearly and the brackets were there to help the reader out. Remove the brackets and that was what the person had really said.
One problem: Rarely, if ever, does the sentence make a lick of sense without the words in brackets. It usually sounds like a 2 year old trying to talk. So do they remove some of the speakers original words when they add the bracketed words? Or what?
Yeah, the brackets can either be inserted or replace actual words. For instance, if the quote was “I think she is a weasel,” you could print it as “I think [Jane Doe] is a weasel” to clarify.
Generally the brackets are used by the writer to indicate to the reader that the writer has paraphrased the speaker in order to (1) maintain syntax or grammar or (2) provide an antecedent that the reader would otherwise have to infer.
For example, if we were talking about the election and said, “I can’t believe he won. I mean, he lost the popular vote, and the Supremes just handed Florida to him”, you would know, having been involved in the conversation, that I was referring to GWB. Someone quoting me for the newspaper, say, can’t assume that readers have that context. So the reporter will write, "Cantrip, in discussing the election, stated that he “[couldn’t] {because I said “can’t”, which doesn’t make sense in this context, but the bracketed word fits syntactically and keeps my meaning} believe [George W. Bush] won.” The second bracket is there because otherwise, although readers might infer I meant Bush, they could just as easily believe it to mean Ronald Reagan.
IIRC, bracketed words are words that are paraphrased from the original sentence. For example, if the person speaking is using expletives, or if the meaning is not entirely clear, and the publication wishes to clarify the meaning of the sentence, the writer of the article will paraphrase in brackets what the speaker meant.
I’m no journalist, but my understanding is that the brackets are used when only part of a sentence is quoted, and that part would not make sense otherwise. So, if you were able to read the entire text of what has been said, there would be no need for the words in the brackets, as all they are doing is putting things back into context.