Sentence case: Capitalize the first word of the text element, as well as any proper nouns.

Title case: Capitalize every word in the text, except:

  • Articles, except as the first word (a, an, the)
  • Coordinating conjunctions (and, or)
  • Prepositions, except the first or last word
  • Infinitives (to, in, an)

To check if you're using title case correctly, put your text into Capitalize My Title using the AP setting.



For desktop browsers, Android browsers, and websites:

Default to sentence case to support scanning and strike a friendlier, more human tone. We sentence case the following:

  • Headlines
  • Buttons

Unless otherwise stated in the word list, please capitalize the following: brands and products (Mozilla, Firefox, Test Pilot, etc.); features (Firefox Screenshots, etc.); acronyms (URL, etc.). URLs (,, etc.) are lowercase. The "a" in Firefox account is lowercase.

Exceptions to sentence casing


Global Operating System menu bar

Title case to align with Operating System conventions

Context menus

Title case to align with Operating System conventions

Android snackbars

All caps (UNDO, DELETE)

Tab audio state


Proprietary product and feature names

- Names are proper nouns, and so should use title case.

- We don’t capitalize features like “new tab,” “shortcuts,” or “passwords,” because they’re not proprietary. Capitalize these words only if they are stand-alone section headers.

In-content pages
(about:preferences, about:logins, etc.)

Currently a mix of title and sentence case — this needs to be redesigned.


For the Firefox iOS browser:

Follow Apple Human Interface Guidelines, which uses headline-style capitalization. Capitalize every word except articles, coordinating conjunctions, and prepositions of four or fewer letters.



System Buttons

Title case.

Acorn Buttons

Title case.

Context Menus

Title case. Apple does not provide specific guidance, but title case seems to be their dominant pattern.

Edit Menus

Title case.

Alert Titles and Messages

- If the title is a complete sentence, use sentence case and appropriate end punctuation.

- If the title is a fragment, use title case and no end punctuation.

- As with all button titles, use title case and no end punctuation.

Information card headlines

Title case.


Title case.