1. Separating Elements:
* Lists: Commas separate items in a list. "I bought apples, bananas, and oranges." Without commas, it becomes "I bought applesbananasandoranges."
* Independent Clauses: Commas separate two independent clauses (clauses that could stand alone as sentences) when joined by a coordinating conjunction (and, but, or, nor, for, so, yet). "The sun is shining, but it's cold outside." Without the comma, the sentence could be interpreted as the sun shining *because* it's cold outside.
* Introductory Phrases and Clauses: Commas separate introductory phrases or clauses from the main clause. "After the storm, the sun came out." Without the comma, the sentence could be interpreted as the sun coming out *during* the storm.
2. Clarifying Meaning:
* Appositives: Commas set off appositives, which are words or phrases that rename or clarify a noun. "My friend, John, is coming over." Without the comma, it's unclear if "John" is a friend or someone else.
* Nonessential Clauses: Commas set off nonessential clauses, which provide additional information but are not essential to the sentence's meaning. "The book, which I bought yesterday, is on the table." Without the comma, it suggests the book *bought yesterday* is the only one on the table.
3. Avoiding Misinterpretation:
* Misreading: Commas can prevent misreading. "The old woman, who had been living alone, was happy to see her grandchildren." Without the comma, the sentence could be interpreted as the woman being *old* because she was living alone.
4. Emphasizing Phrases:
* Parentheticals: Commas set off parentheticals, which are phrases that interrupt the flow of the sentence. "The movie, I must say, was very good." Without the commas, the phrase "I must say" would be more closely associated with "movie."
Example:
"The old man, who had been a soldier in the war, walked slowly down the street."
* Without commas: The sentence implies that the old man is *only* a soldier because he walks slowly.
* With commas: The sentence clarifies that the old man is *both* old *and* a soldier.
In essence, commas act as punctuation guides, ensuring clarity, avoiding misinterpretation, and creating a well-structured flow within a sentence. They play a vital role in shaping the meaning and overall impact of written communication.