Capitalization helps readers identify sentence boundaries, names, and code identifiers. This guide uses sentence case for headings, UI text, tables, and captions. Use this page for questions about sentence case, proper nouns, brand names, and casing requirements.
cap-001 must GuidesAPI docsMarketingBlog Use sentence case for all headings, page titles, navigation items, button labels, and UI text. Capitalize only the first word and proper nouns, and lowercase everything else. A heading that is an API identifier keeps the identifier’s casing (api-member-006).
Examples
Rationale
Title-case conventions vary, so authors can apply them differently. Sentence case is easier to apply consistently and lets proper nouns and code identifiers stand out.
cap-007 should GuidesAPI docsMarketingBlog Use sentence case for captions, figure labels, callouts, list items, glossary terms, glossary definitions, and all table elements: contents, headings, labels, and captions.
Examples
Rationale
Captions, labels, and table text sit next to headings and body text, so a different casing convention for them is visible on every page.
cap-008 should GuidesAPI docsMarketingBlog When a hyphenated word begins a sentence or heading in sentence-style capitalization, capitalize only the first element unless a later element is a proper noun or proper adjective.
Examples
Rationale
Sentence case treats a hyphenated compound as a single unit, so only its first element takes a capital. A proper noun inside the compound keeps its own capital.
cap-011 should GuidesAPI docsMarketingBlog When you refer to a title or heading in content that follows this guide, write it in sentence case even if the original uses title case.
Examples
Rationale
A referenced heading in title case stands out from the sentence-case headings around it. Sentence case keeps citations consistent with the rest of the content.
cap-002 should GuidesAPI docsMarketingBlog Always capitalize proper nouns, including brand, product, and service names, regardless of surrounding capitalization style.
Examples
Rationale
A proper noun’s capital is part of the name. Lowercasing it in a sentence-case heading changes the name.
cap-010 should GuidesAPI docsMarketingBlog When possible, rewrite sentences and headings so they don’t begin with a product or brand name that’s styled in lowercase, such as iPad, macOS, or npm. Preserve the canonical capitalization rather than capitalizing the first letter. If a rewrite produces awkward phrasing, keep the lowercase form at the start.
Examples
Rationale
Capitalization is part of a product name. Moving a lowercase name away from the start preserves its spelling, so the reader can still see where the sentence starts. Capitalizing the name to start a sentence misspells it, which is the larger problem.
cap-004 should GuidesAPI docsMarketingBlog Don’t use internal capitalization, such as AutoScale or e-Book, unless it’s part of an official brand or product name.
Examples
Rationale
A capital in the middle of a word can signal a brand or code identifier. Readers can mistake an ordinary word written that way for a name.
cap-005 should GuidesAPI docsMarketingBlog In body text, use a lowercase letter after a colon unless the text that follows is a proper noun or quotation, or follows a label such as Note or Caution. Titles and headings use a capital after a colon.
Examples
Rationale
Within a sentence, the text after a colon continues the same sentence, so it takes no new capital.
cap-003 should GuidesAPI docsMarketingBlog Don’t use all-uppercase text for emphasis or as a design choice in body text. An abbreviation or a name that is written in capitals, such as API, GPIO, LED, or README, isn’t emphasis.
Examples
Rationale
All caps is harder to read, and a screen reader can spell it out letter by letter, so use emphasis formatting instead. Acronyms and initialisms are capitalized because that is how they are spelled, not to stress them.
cap-012 should GuidesAPI docsMarketingBlog Don’t use all lowercase as a design choice.
Examples
Rationale
All lowercase removes the capital that marks the start of a sentence or a proper noun, so the reader loses both signals.
cap-006 should GuidesAPI docsMarketingBlog When you state a casing requirement, describe it explicitly and give an example. You can also name the casing style, such as camel case, snake case, or dash case, but don’t rely on the name alone.
Examples
maxRetryCount.Rationale
A reader might not know what camel case, snake case, or dash case means, so the description and the example carry the requirement. The style name is useful when paired with them but ambiguous on its own.
cap-009 should GuidesAPI docsMarketingBlog Don’t rely on a difference in capitalization alone to convey a semantic distinction between terms.
Examples
Rationale
A reader can’t reliably tell two terms apart by capitalization alone, and at the start of a sentence or in a heading, both terms take a capital anyway.