My sister, Meg, is coming to visit.
The comma usage in the above statement is correct if I have only one sister.
My sister Meg is coming to visit.
The comma usage in this second statement is correct if I have more than one sister.
Wow! I’ve been exposed to this usage my entire life, yet I’m only now appreciating and understanding it! I learned of this grammar distinction from Grammar Girl, one of my favorite podcasts. If you’re curious about the explanation of this particular rule, check out the February 14, 2013 episode, “Where do I Use Commas?”
Grammar Girl is a concise and surprisingly entertaining podcast on grammar, etymology, and usage. I love grammar, having first gained interest while studying German grammar, which led me to a greater appreciation of English grammar.
Even if you’re no grammarian, this podcast is fun and interesting because it takes something that we use every day (language), and brings understanding to how it works. It’s so interesting to make a study of the ordinary! Furthermore, whatever you learn in this podcast, you can immediately put to use that day in your communications. We communicate with words every day – why not use them correctly?
An additional benefit of Grammar Girl is the opportunity to learn from the creator’s clear and concise method of communication. Within ten minutes she introduces a topic, piques your curiosity, clearly explains the topic, and concludes smoothly. She employs examples expertly, and always seeks to address caveats and challenges to her explanations. Finally, her pacing and flow are top-notch among podcasts.