Numerals

Like this

• You're on a 4 day streak!
• Three dogs begged for treats.
• Over 500,000 U.S. students are learning Spanish on Duolingo.
• 2567 XP

Not this

• You're on a four day streak!
• 3 dogs begged for treats.
• Over 500000 U.S. students are learning Spanish on Duolingo.
• 2,567 XP

Write all numbers numerically, even numbers under 10. But if a number starts a sentence, spell it out. (If it's a really big number like 5,678, rewrite the sentence so it doesn't start with the number.)

If the number is over 999, include a comma. But don't include a comma for XP or other currency totals in the product.

Emoji

Push notifications

Pull from this set of emoji that test well.

Emoji can be placed in either the title (the top line) or the body (the next line), either at the beginning or end of copy. Your call!

Keep it to one emoji. (Unless 2+ makes more sense for the message; see bottom example)

Not every push notification needs an emoji. Omit emoji ~half the time so they don't lose their impact.

Email subject lines

Pull from this set of emoji that test well.

Follow this order: emoji, space, beginning of subject line copy.

A/B test a few subject lines, some with emoji and some without, to determine what gets sent to the full list.

Social media

We can be looser with the rules on Twitter, Instagram, and (less frequently used) Facebook. Use the emoji that match the message, whichever and however many make sense.

Emoji are super useful. They convey information. They grab attention. But a little emoji go a long way.

Punctuation

Don't punctuate headlines, except with an exclamation point.

Like this

• Freeze your streak
• Keep the flame lit!

Not this

• Freeze your streak.
• Keep the flame lit.

Don't punctuate subheads, unless with an exclamation point. If it's a multi-sentence subhead, punctuate each sentence.

Like this

• You're on day 1 of 7
• You're on day 1 of 7. Keep going!

Not this

• You're on day 1 of 7.
• You're on day 1 of 7. Keep going

Never use punctuation in a button.

Like this

• NO THANKS

Not this

• NO, THANKS

Punctuation marks help us break information into readable chunks. They also dictate the tone of our content! (Like so!) We have some hard-and-fast rules for which punctuation marks we use where....and which we really, really try to avoid.

Punctuation

Periods

Like this

• The girl said, "I like chocolate." So do I.

Not this

• The girl said, "I like chocolate". So do I.

Periods go inside quotation marks. Always follow a period with one space, not two.

Punctuation

Dashes

Use a hyphen (-) to join two words, usually to create a compound adjective. Note: Don't hyphenate "x day streak." Don't use a hyphen when the first word of a compound adjective ends in -ly.

Like this

• We live in a split-level house.
• Everyone loves Duo's wildly charismatic personality.
• Keep your 10 day streak going!

Not this

• We live in a split level house.
• Everyone loves Duo's wildly-charismatic personality.
• Keep your 10-day streak!

Use an en dash (–), with no space on either side, to indicate a range. Think of – as replacing the words "through" or "to."

Like this

• The event will be held November 13–15, 6–9 pm each day.

Not this

• The event will be held November 13-15, 6 – 9 pm each day.

Avoid em dashes (—). It's more Duolingo style to have two sentences than one long sentence broken up with a dash. If you must use an em dash, put a space on either side.

Like this

• Using Google Translate is fun. But have you tried learning a new language?

Not this

• Using Google Translate is fun — but have you tried learning a new language?

There are three — yes, three — kinds of dashes. We mostly use hyphens and en dashes.

Punctuation

Colons

Like this

• Lessons are effective: short, fun, and based on learning science.
• Lessons are effective: They're short, fun, and based on learning science.

If the copy following a colon is a fragment, don't capitalize the first word. If it's a complete sentence, capitalize!

Punctuation

Commas

Like this

• Lessons are bite-sized, fun, and effective.

Not this

• Lessons are bite-sized, fun and effective.

Use the serial comma (a.k.a. Oxford comma).

Punctuation

Ellipses

Like this

• Hmm...not exactly.
• Cats can be tricky... They're not exactly obedient.

Not this

• Hmm… not exactly.
• Cats can be tricky...They're not exactly obedient.

We don't use ellipses frequently...but when we do, there isn't a space on either side... But if the ellipsis ends the sentence, add a space.

Punctuation

Semicolons

Like this

• The dog was friendly. It came over to greet me!
• The dog was friendly — it came over to greet me!

Not this

• The dog was friendly; it came over to greet me!

Instead of a semicolon, use an em dash. Even better: Break long, two-part sentences into two simple sentences.

Punctuation

Apostrophes

Like this

• Westeros's weather can be spotty.
• The sax's sound was smooth like caramel.
• The buzz's effect wore off.

Not this

• Westeros' weather can be spotty.
• The sax' sound was smooth like caramel.
• The buzz' effect wore off.

When a singular word ending in s, x, or z has a possessive, put an s after the apostrophe.

Punctuation

Quotes and quotation marks

When writing in English, periods and commas go inside quotation marks. Everything else (!, ?, ;) goes outside quotation marks, unless it's part of the quoted material. Note that other languages have differing conventions for punctuation marks, and we observe them when copy is localized.

Like this

• Some people say "bonjour," while others say the more casual "salut."
• How do you say "hello"?
• She asked him, "Where do you want to go?"

Not this

• Some people say "bonjour", while others say the more casual "salut".
• How do you say "hello?"
• She asked him, "Where do you want to go?"

Include a comma before a quote if the words before it describe the writing or saying of the quote.

Like this

• He said he was going to "school," but he really meant Duolingo.
• He said, "I'm going to school."

Punctuation

Ampersands

Like this

• Learning on Duolingo is fun and fast-paced.
• Tips and tricks

Not this

• Learning on Duolingo is fun & fast-paced.
• Tips & tricks

Avoid using & to replace "and" in copy. One exception is ads with a low character count — but when there is space to write out "and," it is more user-friendly.

Formatting

Formatting is like visual design for copy. These guidelines aren't grammatical rules, but rather how we treat these situations at Duolingo.

Formatting

Capitalization

Put button copy in all caps.

Like this

• CHECK
• DOWNLOAD NOW

Not this

• Check
• Download Now
• Download now

Use sentence case for headers and subheads.

Like this

• Freeze your streak!
• Take a 1 day break from Duolingo without losing your streak

Not this

• Freeze Your Streak!
• Take A 1 Day Break From Duolingo Without Losing Your Streak

Use sentence case for blog post titles and page titles.

Like this

• How are Duolingo courses evolving?
• Learning hub
• About us

Not this

• How Are Duolingo Courses Evolving?
• Learning Hub
• About Us

Use title case for video titles. (This is the norm on YouTube.)

Like this

• Couples Talk Language and Love
• Giving Up Social Media for a Year to Learn Italian

Not this

• Couples talk language and love
• Giving up social media for a year to learn Italian

Use title case for titles of stories.

Like this

• Room for Rent
• Do I Know You?

Not this

• Room for rent
• Do I know you?

We minimize capitalization in an effort to make our product and brand as approachable as possible. That's not to say that everything is lowercase — we do put button copy in ALL CAPS, and most feature names (like Stories) are capitalized.

Formatting

Lists

Before a list, conclude copy with a colon. Don't capitalize or punctuate for lists consisting of phrases or single words.

Like this

• My favorite fruits are:

• apples

  • bananas
  • plums

Capitalize the first word of a list item if it's a complete sentence, and end it with punctuation.

Like this

• People use Duolingo for different reasons:

• Tourists learn key concepts to help them accomplish certain things when traveling.

  • Professionals learn a new language to open the door to more opportunities.
  • Family members learn a new language to help communicate more meaningfully with relatives.

All list items should be formatted identically. So if one fragment, all fragments. If one sentence, all sentences.

Formatting

Bold

Like this

• Click View more to see all of your achievements.
• Visit Achievements to see everything you've earned.

Bold text to refer to UI elements or actions.

Formatting

Italics

Like this

• Some people love the novel Moby Dick, but I prefer the song "Moby Dick" by Led Zeppelin. I discussed this in my recent article "A Tale of Two Moby Dicks," published in Harpoon's Bazaar.

Italicize titles of books, magazines, films, and music albums. Put quotation marks around song titles and article titles. (This may never come up, but it's a good rule to know.)

Formatting

URLs and email addresses

Like this

• duolingo.com
• facebook.com/duolingo
• duo@duolingo.com

Not this

• http://www.Duolingo.com
• www.facebook.com/duolingo
• Duo@Duolingo.com

Leave off the http:// and www., and put the rest of the URL in lowercase. Put email addresses in all lowercase.

Parts of speech

Welcome to the nitty gritty of grammar! Forget what you learned in school: Every brand has its rules for certain word types. And these are ours.

Parts of speech

Contractions

Like this

• You're doing great!
• It's easy to learn Korean on Duolingo.
• Skipping Duolingo lessons for months at a time is not recommended.

Not this

• You are doing great!
• It is easy to learn Korean on Duolingo.
• Skipping Duolingo lessons for months at a time isn't recommended.

Contractions are okay and encouraged. Use them when they make a sentence read more naturally. (In some cases, not using contractions is a strong way to get something important across.)

Parts of speech

Conjunctions

Like this

• Duolingo just turned 7! And we have exciting news to share.

It's okay to start a sentence with a conjunction (and, but, or).

Parts of speech

Prepositions

Like this

• Who are you learning with?

Not this

• With whom are you learning?

It's okay to end a sentence with a preposition (to, for, of, with, etc.) if it reads more naturally.

Etc.

Guidelines for the miscellaneous characters and symbols that work their way into copy.

Etc.

Phone numbers

Like this

• 555-123-4567

Hyphens only, no parentheses.

Etc.

Money

Like this

• $25
• $9.99 a month
• 33 cents a day

Put the dollar sign or other currency symbol in front of the amount. For even amounts, omit .00. If less than a dollar, write x cents.

Etc.

Percentages

Like this

• 95%

Not this

• 95 percent, 95 per cent

Use the % symbol instead of writing out percent.

Etc.

Time

Like this

• 3:00 pm
• noon, midnight

Not this

• 3 pm, 3pm, 3 PM
• 12:00 pm, 12:00 am

Write the numeral and then am or pm, with a space between. If the time is on the hour, write it as :00. Midnight and noon are neither am nor pm, so write midnight and noon on their own.

Capitalization

Consult these charts before hitting the Shift key or Caps Lock.

Capitalization

Capitalize

Features

• Stories
• Leaderboards
• We're bringing back Hearts as the way to track your health on Duolingo.

Achievements

• Sharpshooter
• Wildfire
• Champion
• Inner Circle

Items you buy

• Health Shield
• Streak Freeze
• Timed Practice
• Streak Repair
• Progress Quiz
• Turn on your Health Shield for unlimited health.
• Luckily, Streak Repair kept your streak going.

Add-ons and games

• Club Chat
• Caption That

Specific levels

• Level X
• You've reached Level 3 in Common Phrases 1!

Products

• Podcast
• Duolingo English Test
• Kids
• Events
• Labs
• The Duolingo Kids app is geared for learners 0–13.

Page titles as they appear in the UI

• Achievements
• About us
• Visit Achievements to see everything you've earned. Visit Contact us with any questions.

Generally speaking, we capitalize things that are particular to Duolingo, whether that's an achievement name or a feature type.