Capitalisation within writing
When it comes to writing, editing or proofreading, the rules surrounding capitalisation will naturally come to you as it is a vital aspect of punctuation that is used on a daily basis. Traditionally, capital letters are used to start sentences, denote headings and work titles, and to differentiate proper nouns and names from other words in a sentence. Obviously, the way capitalisation can and will be used will change depending on an author or publisher’s personal preferences – you will be able to find these instructions in the respective style sheet or house guide you are following.
General rules
You should capitalise the first letter of the word that starts a sentence.
The first letter of a completed quoted sentence should be capitalised (e.g. ‘Where did you go?’ John asked.)
Single words and phrases that have been quoted should not be capitalised.
Proper names should usually be indicated by a capital letter, especially if they consist of common nouns and qualifiers.
Capital letters can be used for humour in fiction, however, be wary that the overuse of them can cause misinterpretation.
Specific rules
When a proper name has been capitalised in a body of text, whenever it is referred to again, revert to lower case (e.g. ‘Newcastle University’ changes to ‘the university’.)
Capital letters should be used for institutions, organisations, companies and groups. It should be noted that in this context, the word the should not be capitalised (e.g. the British Museum).
Use lowercase unless it is vital in distinguishing something specific from a general meaning (e.g. ‘Romance’ is to be capitalised in reference to the nineteenth century artistic movement.)
Geography
Regions, areas, features and buildings should be capitalised.
When dealing with rivers and oceans, you should capitalise the full term (e.g. the Atlantic Ocean).
When it comes to locations, the rules surrounding capitalisation can change based on context. Therefore, it is important to thoroughly check the designated style sheet/house guide to make sure you are following the specific style used.
Dates and Days
Days, months, festivals and holidays should always be capitalised.
When naming seasons, use lowercase unless personification takes place.
Historical periods and time scales should be capitalised (e.g. the Middle Ages).
Typically use lowercase for centuries and decades.
Evidently, this blog post doesn’t cover all of the ways in which capitalisation is used within writing, and what to look out for when editing and/or proofreading it. For a full brief, with examples, I would recommend chapter five of New Hart’s Rules: The Oxford Style Guide (2014).