How to classify what type of messages should've a fullstop/period and what should not?

Because there are certain error/warning/success/info messages (be it a dialog, banner, contextual or ones in a separate page that appears between a workflow) that needs to be framed in two or more sentences that obviously requires a full stop.

MS Windows generally in their alert dialogs have two parts - an alert message coupled with an informative message. The alert message will be succinct and in a single sentence that won't have a fullstop. But the informative message will have at its end.


6 Answers 6


The only place where you don't use a full stop is in titles (such as in the title bar of a window). In all other cases, you need proper punctuation.

Compare it to a book: the title of the book does not end with a period, all sentences inside do end with punctuation. Except the titles of the chapters, which are titles again. I remember in elementary school putting a period at the end of the title of your paper was considered an error by the teacher, resulting in a lower grade.

You are stating: "MS Windows generally in their alert dialogs have two parts - an alert message coupled with an informative message."

Could you please post a screenshot of such a message? I cannot think of any example to be honest...

Update: taking into account krishnajay's comment, this should be the correct answer:

enter image description here

  • 3
    Refer msdn.microsoft.com/en-us/library/windows/desktop/aa511267.aspx for windows messages
    – krishnajay
    Mar 14, 2012 at 18:45
  • 1
    Here is the rule... //Don't include final periods if the instruction is a statement. If the instruction is a question, include a final question mark.//
    – krishnajay
    Mar 14, 2012 at 18:48
  • @krishnajay: what is your source? Do you have a reference for that? Mar 15, 2012 at 6:51
  • You are right. Mind that this is only for the "main instruction", not for the "supplemental instructions". Most of the time, when using standard messageboxes, there is not main instruction. Mar 15, 2012 at 6:57
  • So does it mean all messages should've a main instruction and it shouldn't be in multiple sentences. If there is a need for multiple sentences, is it supposed to be split? Moreover does it apply for contextual messages such as the ones displayed below the input fields
    – krishnajay
    Mar 15, 2012 at 7:26

If it's a proper sentence, give it proper punctuation.


Though Bart was pretty spot on with his answer, here are some guidelines given by MSDN with regards to Error and Informational messages. To quote them:

  • Identify the problem, indicate the cause if helpful, and provide a solution if possible.
  • Write phrases instead of complete sentences to conserve space. For example, write "Save using a different name" instead of "Save this document using a different file name." Use title caps in the title bar of the message box and sentence caps in the message body text.
  • Title caps rules specify that all words are capitalized with the exception of articles, coordinating conjunctions (and, but, for, not, or, so, and yet), and prepositions containing four or fewer letters.
  • Sentence caps rules specify that only the first word and any proper nouns are capitalized.
  • Bold command names instead of using quotation marks.
  • When there may be a consequence of a user's action, preface the error message with the word "Warning." For example, write "Warning: If you synchronize now, duplicate items may appear in your Inbox."
  • Do not use exclamation points.
  • Do not write content that implies that applications can think or feel.
  • Avoid using the word please. Also, use the following alternative terms for abort, boot, and reboot.

Also if you go by the Error Messages guidelines for Windows,the only place where periods are supposed to be used is when

Don't include final periods if the instruction is a statement. If the instruction is a question, include a final question mark.

You might also want to see what MSDN recommends for Capitalization and Punctuation Guidelines

End punctuation (. ? !) : Use ending punctuation only in instructional text.

  • Yes I've gone through their guideline. But how about Apple? Do they follow a similar approach?
    – krishnajay
    Mar 19, 2012 at 11:10

To me, a sentence is required to end with a period to distinguish it from the next sentence in a paragraph. If there is only one sentence, and a short one at that (e.g. "Error while downloading file") then why do we need a period at the end? If you have Growl-type notifications, the sentences are already enclosed in a dialog box. This is not poetry or literature, these are just short-lived notifications.

I went through our application messages (warnings, errors, confirmations, etc.), I was sure I didn't need to put a period (full-stop) at the end. I'm all about proper grammar and syntax and I never type even popular abbreviations in my messages, but this is a different story.

Not to mention the following: http://www.newrepublic.com/article/115726/period-our-simplest-punctuation-mark-has-become-sign-anger

Oh, and in the example mentioned by Bart, there are 2 or 3 parts indeed, and the answer is clear, but what if you have only one sentence, no titles or anything else?


This is what the Apple Human Interface Guidelines for iOS have to say about this:

If you must provide an optional alert message, write a short, complete sentence. If possible, keep the message short enough to be displayed on one or two lines. If the message is too long, it will scroll, giving users a poor experience. Use sentence-style capitalization and appropriate ending punctuation in the message.

Note that in all the screenshots in the HIG for both OSX and iOS, the explanation text is a sentence and ends with a period. See the appropriate section in the OSX HIG for more examples.

  • I can not see your quoted message in the links you provided
    – newlog
    May 18, 2017 at 15:46
  • @Newlog It appears Apple moved everything around and broke that link - which now has a generic redirect to the iOS HIG landing page :( May 18, 2017 at 16:07
  • I updated the links to point to the current locations. Jun 7, 2018 at 22:04

Here's something to consider. All web pages should be designed to be accessible which means they should work well with a screen reader. So let's say you have a modal with a detail message that's a full sentence and then a Close button. Without a period after the full sentence, you might hear "The input XYZZY is not allowed close" With the period, you will here "The input XYZZY is not allowed. Close" There will be a short pause after the period. That greatly increases understandability.

I concur with recommendations above that the short error title should not have punctuation but the detailed message should be worded as a full sentence and should have a period.

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