The Editor's Manual
Grammar, usage, punctuation, and style resource for editors, writers, and learners of the English language.
Don’t use a comma before “who” when it presents information necessary to meaning (a restrictive clause). Do use a comma when “who” introduces an optional description (a nonrestrictive clause).
Use “that” as a relative pronoun in restrictive or defining clauses, which present information essential to meaning. Don’t use a comma before “that.”
Don’t capitalize a word after a colon within a sentence, or a single sentence after a colon. Capitalize a question or a series of two or more sentences introduced by a colon. Also capitalize subtitles.
Various grammatical forms can function as the subject in a sentence. The subject can be a noun phrase, a noun clause, or a prepositional phrase.
The subject is implied in imperatives (“Please wait here”), certain elliptical constructions (“See you later”), and some nonfinite clauses (“Rita waited, holding her breath”).
It is grammatically fine to use “because” at the start of a sentence. Just remember to write a complete sentence, and avoid using a pronoun before its noun.
Conjunctions link words, phrases, clauses, and sentences, and show a logical relation between them. Coordinating conjunctions (e.g., “and,” “but”) link elements of equal grammatical status, while subordinating conjunctions (e.g., “because,” “though”) make one clause depend on another for complete meaning.
Use commas to make lists, set off phrases, separate clauses, and indicate that a detail is nonessential in a sentence.
Use a comma between the items in a list, to separate two independent clauses, and after a subordinate clause. Enclose nonessential phrases and clauses in commas.
Use a semicolon in place of a period to join two closely related sentences. Also use it to separate list elements that themselves contain punctuation.