Traditional Rule:
* Use a comma before the conjunction "and" in a series of three or more items.
Example: I bought apples, oranges, and bananas.
Modern Usage:
* The comma before "and" in a series is often omitted, especially in shorter series. This is increasingly common in informal writing and speech.
Example: I bought apples oranges and bananas.
Why the Change?
The traditional rule was based on clarity and avoiding ambiguity. However, with the rise of concise writing and a more relaxed approach to punctuation, many writers and editors now consider the comma before "and" optional in most cases.
When to Use a Comma:
* Clarity: If omitting the comma could lead to confusion or misinterpretation, use it. For example: "I went to the store, bought some bread and cheese, and then went to the park." (Without the comma, it might seem like you bought cheese at the park).
* Style: If your writing style dictates a more formal tone, the comma before "and" is generally considered more appropriate.
* Emphasis: You can use the comma for emphasis, even in a short series. For example: "She wore a bright yellow dress, a wide-brimmed hat, and a big smile."
When to Omit the Comma:
* Short series: In a very short series (like two items), the comma is often unnecessary. For example: "I bought apples and oranges."
* Informality: In informal writing or speech, the comma before "and" is often omitted, even in longer series.
In Conclusion:
The comma before "and" in a series is a matter of style and clarity. While the traditional rule still holds true, modern usage often omits the comma, particularly in informal writing and shorter series. Consider your audience, your writing style, and the potential for ambiguity when making this decision.