Essential tips for punctuation. For more detailed guidelines, refer to the AP Stylebook or the Microsoft Writing Style Guide.
Use them! Just don’t overuse them. Exclamation marks, used in moderation, can help give your product copy a more human and personal tone of voice.
In most product copy, sentences should be so short that a comma isn't needed. Short sentences with very little punctuation should be the aim. If you feel like a sentence really needs one, try reworking the sentence first.
And drop the Oxford comma, unless it adds clarity.
When you use a colon within a complete sentence, the first letter after the colon should be lower case. Exception to this would be if it’s a headline or the first word is a proper noun.
Make sure to add a colon at the end of every sentence that precedes a list, numbered or bulleted.
Use them sparingly. Or maybe not at all! They usually support longer, complicated sentences that could easily be simplified. Try solving this by starting a new sentence. If you aren’t fully confident that a semicolon works, don’t use it.
Use en dashes to connect numbers. Use hyphens to connect words. Use em dashes, with no spaces before or after, to amplify a thought. Em dashes are slightly longer than en dashes, which are slightly longer than hyphens. Who knew that there were so many uses for that tiny horizontal line.
When including an amount of money in text, use the symbol and don't spell out the currency. If you need to indicate the currency, place it before the currency symbol, and in the short form. Follow the rules in the Numbers section for how to display the amount.
Spell out numbers from one through nine and use numerals for 10 and up.
Express large and very large numbers in numerals followed by million, billion, and so forth. If expressing a number in the thousands, use a comma.
Spell out the day of the week and month, and only include the year if it occurs in a future or past year. Do not abbreviate days or months, and leave out ordinals (st, nd, th, rd).
Always use "a.m." and "p.m." for indicating time. Always add a space between the number and a.m. or p.m. If the start and end times are both in the a.m. or p.m., only include the qualifier for the end time. Connect time spans with an en dash.
Always use double quotation marks. Periods, commas, question marks and exclamation marks go inside the quotation marks.