Grammar and punctuation

Firefly follows the conventions that are taught to our students, so our grammar and punctuation matches what they are familiar with in class.

# Grammar

English style

Use modern British English. If you need to check to see which spelling to use of common words, the Ngram Viewer can help you track usage over time.


In the product, always use the numeral. In other communications, use numerals for double-digit numbers or larger. If you are describing a measurement, use the numeral. To increase readability, use commas in four-digit numbers or larger.

Latin terms

Use sparingly. If possible, use the English terms. ‘For example’ should be used instead of ‘i.e.’ or ‘e.g.’ whenever possible. Use ‘through’ or ‘using’ instead of ‘via’. Marketing and communications can use these terms more frequently but should make sure they use them correctly.

Abbreviations and initialisms

Know your audience. If your readers will be familiar with a term (GCSEs, for example), you can use it confidently. If your users might be unfamiliar with a specific abbreviation or initialism, introduce it fully in the first instance and add the abbreviation immediately following in parentheses, without full stops. After that point, you can use the abbreviation throughout the document.

# Punctuation

Serial comma

Do not use the serial comma (also known as the Oxford comma) in a list.

Quotation marks

Use double quotation marks for something said. Use single to quote a line written in copy.

Exclamation marks

Use sparingly. Greetings such as ‘Welcome!’ are okay.


Do not put an extra space between slashes (example: teachers/faculty). Whenever possible, avoid slashes and use ‘or’ instead.

Full stops

Use only one space following a full stop. Don’t use full stops in the UI unless you have multiple complete sentences.

Colons or semicolons

Make sure they are used correctly. Do not capitalise the word following a colon or semicolon unless using a proper noun.


Use sparingly. In the product, only use to signal that the text or response has been truncated.


Only used to separate an interruption from the rest of the sentence. Use a pair if it comes in the middle of a sentence, just one if it comes at the end. Requires a blank space on each end.


Used to combine two or more words when they directly precede and modify a noun (examples: ‘up-to-date spreadsheet’, ‘third-party system’). Also used for some compound nouns, such as ‘co-owner’. ‘Email’ should not be hyphenated.