From The Grammarly Blog:
English capitalization rules require that certain words, like proper nouns and the first word in a sentence, start with a capital letter. Although that seems simple, some words are capitalized only in certain situations, and some words seem like they should be capitalized but are not—how can you tell which is which?
In this guide, we explain how to capitalize when writing and cover all the English capitalization rules. We also share a list of what words need to be capitalized and provide a few capitalization examples. But first let’s talk a little about capitalization in general.
English capitalization rules: When to capitalize
Knowing which types of words to capitalize is the most important part of learning English capitalization rules. Basically, there are three types of words you capitalize in English:
the pronoun I
the first word in a sentence or line of a letter (e.g., Sincerely )
proper nouns
That last one, proper nouns, is where a lot of the confusion comes from. Some words, like the name Albert Einstein , are always capitalized; however, others are capitalized only in certain situations and are lowercased in others. For example, directions like north and west are normally lowercased but are capitalized when they’re used as part of a geographic name, like the West Coast .
Let’s take a closer look at what words need to be capitalized and when.
What words need to be capitalized?
People’s names
Both the first and last names of a person are capitalized. Likewise, middle names, nicknames, and suffixes like Jr. are also capitalized.
Martin Luther King Jr.
Dwayne “The Rock” Johnson
Historical names that include descriptive words often follow the rules for title capitalization: Prominent words are capitalized, but small words like the or of are not.
Ivan the Terrible
Maria of Aragon
Titles
Capitalization in titles is where a lot of capitalization errors come from. The title of any piece of work—books, movies, songs, poems, podcast episodes, comic-book issues, etc.—requires capitalization, but only certain words in the title are capitalized.
What words need to be capitalized in titles? For starters, the first word in a title is always capitalized. Nouns, pronouns, verbs, adjectives, and adverbs all need to be capitalized in titles as well.
Small words like articles and prepositions are generally lowercased, unless they’re the first word in a title. However, some style guides have their own preferences, so double-check if you have any doubts.
The Catcher in the Rye
Of Mice and Men
Places
If you’re using the name of a place, capitalize it. This applies to everything from tiny Deer Creek to the massive planet Jupiter.
New York City
Lake Victoria
Keep in mind that if you are not using the name of a place but the general word to describe it, you do not capitalize that word.
The Grand Canyon is a good canyon, but I wouldn’t call it “grand.”
Countries, nationalities, and languages
In English, countries, nationalit ies, and languages are capitalized. Country names fall under the category of places, but by extension the names of the people who live there and the adjective form of their culture are also capitalized. This includes languages.
Haiti
a team of Haitians
Haitian cuisine
Link to the rest at The Grammarly Blog

