Here's why:
* Clarity: Placing punctuation outside the parentheses makes it clear that the punctuation marks the end of the sentence, not the citation itself.
* Standard practice: This is the standard format recommended by most style guides (e.g., APA, MLA, Chicago).
Example:
* Incorrect: "This is a sentence (Smith, 2023). "
* Correct: "This is a sentence. (Smith, 2023)"
Exceptions:
There are a few exceptions to this rule:
* Direct quotes: If the citation is part of a direct quote, the punctuation goes inside the quotation marks and before the parentheses.
* Parenthetical statements: If the citation is part of a parenthetical statement within a sentence, the punctuation goes after the parentheses.
Remember: Always consult the specific style guide you're using for the most accurate and up-to-date formatting rules.