Basic Punctuation Rules

The goal of standard language is to allow efficient communication. To avoid that individuals need to first agree upon a protocol every time they want to talk to each other, standard language was invented with standard rules. If you believe it is OK to deviate from those rules and invent your own punctuation, words, or even entire language, I have only one thing to say to you:

Punctuation helps to make written text easier to parse. Standard punctuation rules make every text equally easy to parse with no surprises, as long as every text follows those same rules. A text that deviates from the rules is harder to parse, hence harder to read and harder to understand.

Next to clueless people who make a wild and random guess every time they have to start a new sentence, there are also the more curious examples of people who strictly abide by their own invented syntax. A nice example is a mail I received where someone never used capitals, and never typed spaces after punctuation marks. The result was that whenever he started a sentence with “it,” I believed he was pointing to some Italian website like ‘link.it’ or ‘amazon.it’. To add insult to injury, my mail program thought alike and made the unintended links clickable. Confusion is not a basis for good communication.

Therefore, a simple list of very basic punctuation rules that apply to the majority of languages written in Roman script.

In short:

1. Every new sentence starts with a capital. Besides this, only names are capitalised.
2. Every sentence ends with a period, question mark, or exclamation point (or very occasionally, an ellipsis).
3. A period, comma, question mark, … is followed by one space.
4. Brackets or quotations: spaces on the outside, none on the inside.
5. Divide your text into paragraphs that make sense.

The long version with bad examples:

1. Every new sentence starts with a capital. Compare the difference between this chunk of text and the one that follows. You will see that it is much more obvious where a new sentence starts.
   every new sentence starts with a capital. compare the difference between this chunk of text and the one that precedes. you will see that it is much less obvious where a new sentence starts.
   Some Like To Take It To The Other Extreme And Capitalise Every Word. This Is Equally If Not More Annoying. Don't Do This.

   In case you start a sentence with a number, do not capitalise the first word that comes after the number. Consider the number capitalised. Of course, it is better to avoid starting a sentence with a number altogether, or to write that number in full. Compare the next examples. 2 ways to start a sentence with a number. Two ways to start a sentence with a number.

   The only other words in a sentence that should get capital letters are names. Some languages may have additional rules for capitalisation, for instance in German every noun is capitalised.

   Note that in accordance with the item below, no capitalised word must follow after a comma, colon, semicolon, dash, or other punctuation mark that does not indicate the definitive end of the previous sentence, except if the word is a name. This means the following is correct. WARNING: do not capitalise the word “do” here.

2. Every sentence ends either with a period (also known as full stop), question mark, or exclamation point. Very occasionally it may end with an ellipsis… Some people end almost every other sentence with an ellipsis… It is as if they are constantly pausing, looking for words… It is very annoying. Prematurely ending a sentence in an ellipsis can be a nice style element, but do not overdo it. Try to limit it to at most once per equivalent of one page of text. Of course it is OK to use an ellipsis more often as a means to indicate an incomplete enumeration. Depending on how it is used, an ellipsis may or may not end the sentence.
   in case you thought punctuation is purely decorative try reading this chunk of text it basically looks like a random thought dump are you still following me hey look a bird in the sky you probably get the point that this is not the kind of text you want to send to anyone whose attention you want to keep for longer than five seconds

   A side note about the ellipsis: although it looks like a sequence of 3 periods, it actually is a punctuation mark on its own. It is OK to simply type 3 dots (not 2 or 4), but many input methods allow to directly enter the ‘horizontal ellipsis’ Unicode character. For instance on a Mac U.S. keyboard layout, it can be entered by holding down the alt key and typing a semicolon ‘;’.

   Regarding abbreviations at the end of a sentence: the last period of the abbreviation also serves as the period ending the sentence. Never try to use 2 periods, otherwise your punctuation will be F.U.B.A.R.

3. Every punctuation mark like a period, comma, question mark, … is followed by one space. There is no space before the mark⁽¹⁾. If you want, you can put two spaces after a period that indicates the end of a sentence (although this practice from the typewriter era is generally frowned upon nowadays). The only exception is periods inside abbreviations: do not use spaces until the end of the abbreviation (e.g., S.N.A.F.U.)
   Compare the previous with the following:every punctuation mark like a period,comma,question mark,…is not followed by one space here.for fun i also dropped capitals.do you like reading text written like this?i think not.
4. An opening bracket or quotation mark is preceded by one space. A closing bracket or quotation mark is either followed by a space or a punctuation mark (like this) and “like this”. No spaces at the inside of the brackets or quotation marks.
5. When you change the subject within a text, even if only slightly, start a new paragraph. You should develop an automatic urge to hit the “return” key after you have typed about five sentences. Depending on the software you are using, you may need to type either one or two returns to start a clearly visible new paragraph. Obviously, you should not exclusively write five-sentence paragraphs. It is perfectly OK to write something much longer from time to time, but if you consistently produce lumps of dozens of sentences, your text will look very uninviting to any reader.

⁽¹⁾: About spaces before question marks and exclamation points: some style guides, especially in French, will suggest to put a space before these two symbols, as well as colons and semicolons. However, in most other languages the rule is to omit the preceding space. A problem with adding a space is also that in typed text that could be displayed inside a variable width text field, the space could cause the punctuation mark to drop to the next line.

There are some region-dependent rules as well about whether a comma, full stop (period), or other punctuation mark ending a sentence should be inside or outside a quoted phrase. Look them up if you want to be sure, but obviously this is only a detail. The above rules are far more important.