You should use a comma in the following key situations:
- To separate two independent clauses joined by a coordinating conjunction (and, but, yet, so, or, nor, for). For example: "He walked down the street, and then he turned the corner."
- After an introductory clause, phrase, or word that precedes the main part of the sentence. For example: "When Evan was ready to iron, his cat tripped on the cord."
- To separate items in a series of three or more. For example: "We bought apples, peaches, and bananas today."
- To set off non-essential or non-restrictive clauses and phrases that add extra information but are not critical to the sentence meaning. For example: "Edinburgh, the capital city of Scotland, is famous for its castle."
- To separate coordinate adjectives that equally modify a noun. For example: "It was a long, tiring journey."
- To separate parts of dates, geographical names, titles, and direct addresses. For example: "On Tuesday, April 13, at three o’clock, there will be a meeting."
- To separate elements in compound sentences and to clarify meaning or prevent misreading.
- To set off interrupters or parenthetical elements within a sentence for clarity.
Avoid using commas where they separate a verb from its object or essential elements without which the sentence meaning would change. A comma generally indicates a pause in speech and helps make your writing clearer, more readable, and more precise. These guidelines reflect common rules to use commas effectively in writing.
