Capital letters are used to give prominence to particular kinds of words. They are used:

  • to mark the start of a sentence
  • to identify proper nouns and proper names
  • to identify common nouns that refer to distinctive entities or roles in a given context
  • in initialisms and acronyms.

This section covers:

See Date and time systems for use of capitals in calendars, historical time periods (e.g. BCECE21st century) and ages (e.g. Stone AgeMiddle Ages).

See History of Earth for use of capitals in geological timescales (e.g. Early JurassicPleistocene Epoch).

See Headings for use of capitals in headings.

Reminder. Initial capitals are generally only used for full formal names (e.g. Senator John Smith, Department of Health). Generic and collective (plural) references to the same item do not need capitals (e.g. the senators left town, he left the department).

The golden rule is to maintain consistency throughout the publication.

Use of capital letters in scientific terms is discussed in the sections relevant to science editing, including: