Quotation marks have that name because they are used when you want to quote someone word for word with no changes whatsoever.
Here’s an example:
“Be at the station at exactly six thirty,” said Mary.
It would be equally correct to say:
Mary told Bill to be at the station at 6:30.
In the first sentence, the writer has chosen to use Mary’s words, and that’s why they’re in quotation marks. Grammarians call this direct speech, whether we are talking about written or spoken words.
In the second sentence, the writer is telling the reader what Mary said but summarized what Mary said in his or her own words. Grammarians call that indirect speech.
Sometimes, we use quotation marks to indicate that a word or phrase is being used inappropriately. For example, your friend, Alex, tells you she has a business. You notice that she lives with her parents and never seems to have any money. She gets up at ten; plays with her computer for a couple of hours; and then she goes out to be with her friends. One day, you send her an email inviting her to have lunch with you. She writes back telling you that she’s far too busy. In view of her habits, you find this irritating, and you reply asking her if she’s too busy with her “business.”
Those quotation marks carry lots of meaning. You use them because you are acknowledging the fact that Alex uses “business” to describe the time she spends catching up with her Facebook friends, and you really don’t believe a word of it. When speaking, people sometimes have an annoying habit of waggling their fingers in the air to create this effect!
Last night, I saw a sign that said:
TO OUR “VALUED” CUSTOMERS
Of course, I knew what the writer meant, but I smiled because I also knew that, if the quotation marks were being used correctly, it would mean that the customers weren’t valued at all.
Funnily enough, someone has created a whole blog devoted to amusing examples of unnecessary quotation marks. Check it out. It often makes me laugh.