According to some grammars[1][2] and CMS...

"Interjections and vocative should be separated from the rest of the sentence by commas".

The vocative case [1] is used to indicate direct address (i.e., to show when you are talking to somebody or something directly). Nouns in the vocative case are set off using commas. CMS 6.38

As direct address (i.e. vocative case), the parenthetical element should be set off using commas (CMS 6.30). An absolute phrase is always treated as a parenthetical element, as is an interjection.


Hello, world!

That is a very classical way to hello the world.

But, languages change. I am not sure, but today, I feel that it is very uncommon helloing someone with an interjection, providing a small pause and clarifying who is helloed. I have an impression that usually people use hello as a ("kind of") verb, not an interjection.

Question: Is that just a personal (bad) impression or some linguistic has already studied that phenomenon?

  • [1] - Nelson, Gerald C., Director Survey of English Usage Sidney Greenbaum, and Sidney Greenbaum. An Introduction to English Grammar. Routledge, 2013.
  • [2] - Advanced Grammar in Use with Answers: A Self-Study Reference and Practice Book for Advanced Learners of English. 3 edition. Cambridge University Press, 2013.
  • CMS - Chicago Manual of Style
  • English doesn't have case, except for the pronouns, which don't have a vocative case. Oct 19, 2015 at 14:34
  • 1
    Vanishing from what would be my question. It's still called for by CMOS and AP and I presume other style guides, though I don't come across direct address in newspapers and magazines very often. If it's disappearing from hello, world in software manuals, perhaps that's because, like howdy-do, what originated as a sentence can now be treated as a noun in and of itself: The examples compare the syntax of a hello world function in C++ and Objective-C.
    – choster
    Oct 19, 2015 at 15:02
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    I don't know who downvoted, but it was possibly for the unsupported and possibly unresearched 'grammar is obvious [regarding the acceptable practice here]' claim. People here on ELU also dislike the conflation of grammar with punctuation. // Personally, I don't think there's much of an argument for a comma being necessary or prohibited here, especially on ease of reading / disambiguation of senses grounds. I'd use a comma if I wanted to signal a reasonable pause, and omit it if not. The hip pronunciation here being hel-lo-world, the comma is misleading. Oct 19, 2015 at 16:00
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    @EdwinAshworth, I tried to polish my questions regarding your observations. Maybe it could be more "likeable" for ELU community taste.
    – rdllopes
    Oct 19, 2015 at 17:10
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    No, it's not vanishing in regular writing (everything is vanishing in txtspeak). "Bob, is that your uncle?" is correct not "Bob is that your uncle?". Or "Is that your uncle Bob?" vs "Is that your uncle, Bob?" for two totally different meanings.
    – Mitch
    Oct 20, 2015 at 15:10

1 Answer 1


I don't know about the vocative aspect but the Chicago Manual of Style advises that a “direct address” should be set off by commas. A direct address occurs when you call someone by a name or other term used like a name. So in your example, "Hello, world," that comma is correct. However, I frequently see the comma being dropped in everyday communication.

  • That also my perception (and It is not only in writing English) but is there any research/study about that!?
    – rdllopes
    Oct 19, 2015 at 14:51
  • 3
    ...that comma is "correct" according to CMS. But there are obviously those who disagree. One issue is that although a comma is implicit in how a greeting like Hello world is said, when it's read a comma introduces too much of a pause.
    – Andrew Leach
    Oct 19, 2015 at 14:54

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