1. Every sentence begins with a capital letter.
2. Every line of poetry begins with a capital letter.
3. The first word of every direct quotation begins with a capital letter.
Note. This rule does not apply to quoted fragments of sentences.
4. Every proper noun or abbreviation of a proper noun begins with a capital letter.
5. Most adjectives derived from proper nouns begin with capital letters; as,—American, Indian, Swedish, Spenserian.
Note. Some adjectives derived from proper nouns have ceased to be closely associated in thought with the nouns from which they come, and therefore begin with small letters. Thus,—voltaic, galvanic, mesmeric, maudlin, stentorian.
6. Every title attached to the name of a person begins with a capital letter.
7. In titles of books, etc., the first word, as well as every important word that follows, begins with a capital letter.
8. The interjection O and the pronoun I are always written in capital letters.
9. Personal pronouns referring to the Deity are often capitalized.
Note. Usage varies: the personal pronouns are commonly capitalized when they refer to the Deity, the relatives less frequently. The rule is often disregarded altogether when its observance would result in a multitude of capitals, as in the Bible and in many hymn books and works of theology.
10. Common nouns and adjectives often begin with capital letters when they designate the topics or main points of definitions or similar statements. Such capitals are called emphatic (or topical) capitals.
Note. Emphatic (or topical) capitals are analogous to capitals in the titles of books (see Rule 7), but their use is not obligatory. They are especially common in text-books and other elementary manuals.