Commas are quite small, yet they pack a lot of punch as far as being able to completely alter the meaning of a sentence.
Let’s say you wanted an iPhone and were forced to sign a contract with its sole service “provider” AT&T. And let’s say that the coverage with AT&T is so bad that you regret having signed a contract with them. You might say:
I’m sorry I have AT&T.
Now, let’s say you’re on the phone and because you have AT&T the call keeps dropping out. You want to apologize to the person with whom you are trying to communicate. You take the same sentence and simply add a comma:
I’m sorry, I have AT&T.
The sentence no longer expresses regret for having a two-year contract with a shoddy mobile phone company but instead tells the individual you had hoped to have a conversation but can’t because your shoddy mobile phone company won’t let you.
All that from a little comma!
Next week we’ll talk about how putting quotes around a word suggests you’re being facetious.