One common English grammar rule is that all sentences begin with a capital letter. Titles of people, books, magazines, movies and proper nouns are also capitalized. Every sentence must end with a punctuation mark, such as a period, exclamation point or question mark.
Colons are a punctuation mark and are used between two clauses if the second clause explains the first, or as an introduction to a list of items or a direct quote containing several sentences. Semicolons are a type of punctuation used to separate a second independent clause that typically begins with an introductory word, such as "therefore." Commas separate words in a series, are used when addressing a specific person and separate a city from its state. Parentheses set apart words that clarify something within the sentence or enclose numbers and letters in a list. An apostrophe indicates a contraction of two words or shows possession.
A sentence requires a subject and a predicate and must express a complete thought in order to stand on its own. Singular subjects require singular predicates while plural subjects require plural predicates. The subject is the focus of a sentence, such as a person, animal or object. The predicate is the word or words that express action or indicate something about the subject.