There are a few specific cases where words should be capitalized. They’re easy to remember. In English, capital letters are most commonly used at the start of a sentence, for the pronoun I, and for proper nouns.
The First Word of a Sentence
You should always capitalize the first letter of the first word in a sentence, no matter what the word is. Take, for example, the following sentences: “The weather was beautiful. It was sunny all day.” Even though the and it aren’t proper nouns, they’re capitalized here because they’re the first words in their sentences.
The Pronoun I
Pronouns are words that replace nouns. I, you, and me are all examples of pronouns. While you and me are usually lowercase, the pronoun I should always be capitalized, regardless of where it appears in a sentence.
For example, in A Beautiful Mind, Sylvia Nasar writes, “What I got back was an envelope on which my address was written in different-colored crayons.” Here, the pronoun I is correctly capitalized even though it isn’t at the beginning of the sentence.
A proper noun is the special noun or name used for a specific person, place, company, or other thing. Proper nouns should always be capitalized.
People’s names are proper nouns, and therefore should be capitalized. The first letter of someone’s first, middle, and last name is always capitalized, as in John William Smith.
Other proper nouns include countries, cities, and sometimes regions, such as Bulgaria, Paris, and the American South. Geographic features that have names should also be capitalized, as in Mt. Kilimanjaro and the Pacific Ocean.
Landmarks and monuments also start their proper names with capital letters, such as the Empire State Building and the Golden Gate Bridge. Street names are always capitalized, too (e.g. Main Street).
The names of companies and organizations should also be capitalized, such as Nike and Stanford University. There are some exceptions: Sometimes a company may choose not to use a capital letter at the beginning of its name or product as a stylistic choice. Examples include eBay and the iPhone.
Titles like Mr., Mrs., and Dr., should be capitalized. When addressing someone with their professional title, you should use a capital letter at the beginning. For example, you’d address a letter to the president as “Dear President Obama.” Similarly, you should capitalize job titles when they come before a person’s name, as in “General Manager Sheila Davis will be at the meeting.” Also use a capital letter when you’re directly addressing a person by their title without using their name, as in “We need the paper, Senator.”
Words that indicate family relationships should also be capitalized when used as titles in front of a person’s name. However, if you’re just talking about relationships with no names involved, the titles shouldn’t be capitalized. For example, you’d capitalize “Uncle Ben and Grandpa Ed will be at the picnic,” but you wouldn’t capitalize them in a sentence like “My uncle and my grandpa will be at the picnic.” Similar to the rules for professional titles, you should capitalize the names of family titles when they’re used in place of proper names. For instance, in Jane Eyre Charlotte Brontë writes, “She is at the lodge, Aunt.”
The titles of books, songs, newspapers, and works of art should all be capitalized. Examples include Moby Dick, “Jailhouse Rock,” New York Times, and The Last Supper.