Capitalization Rules: When to Use Capitals

Every complete English sentence begins with a capital letter, even when the opening word is a short conjunction or article such as and, but, or the. When you finish a sentence with a period, a question mark, or an exclamation point, the following word must also begin with an uppercase letter. This boundary helps readers separate distinct thoughts without confusion.

The personal pronoun I is always written as a capital letter in English, regardless of its position in a sentence. Whether it stands at the beginning, appears after a comma, or pairs with another person in a compound subject, it never changes to lowercase. Writing a small i is common in informal messaging, but professional correspondence requires uppercase I.

You can practise this again in Proper Nouns: Capitalization Rules and Uses and Personal pronouns: rules and examples.

People's individual names are proper nouns that always take capital letters, such as Carlos, Priya, or Sarah. Words describing family roles or relationships, such as mother, brother, cousin, or friend, remain lowercase when used with a possessive word like my, his, or our. You only capitalize a family role word when you use it directly as a personal name without a possessive.

Specific geographical names, such as countries, cities, streets, rivers, and oceans, require capital letters because they identify single locations. In contrast, general words describing types of places remain lowercase unless they form part of an official name. For instance, write river in a general sentence, but capitalize Mississippi River when naming the specific body of water.

Days of the week and months of the year always begin with capital letters because they are proper nouns in the calendar system. In contrast, the four seasons, spring, summer, autumn, and winter, remain lowercase in English unless they appear at the very start of a sentence or form part of an official festival title. Confusing seasons with calendar months is a frequent learner mistake.

Names of languages, nationalities, and ethnic groups always begin with capital letters in English. This rule applies whether the word functions as a proper noun or as an adjective describing food, literature, or origin. General academic subjects like science, history, or mathematics remain lowercase unless they include a language name or form an official course title.

A job title takes a capital letter only when it stands directly before an individual's name as a formal title. If the title appears on its own, follows a name, or describes a general occupation, it remains lowercase. For example, write Doctor Gomez when using the word as a direct title, but write the doctor when referring to the profession generally.

Official organizations, companies, universities, and registered brand names require capital letters for each principal word. General descriptions of organizations remain lowercase. For instance, write Boston University when naming the institution, but write an urban university when describing the type of school. Minor words within an official name, such as of or and, usually stay lowercase unless they start the phrase.