By DON K. FERGUSON, NEWS SENTINEL May 29, 2005
The apostrophe differs from most punctuation marks by appearing as part of a word or number. Most punctuation marks separate words or numbers.
An apostrophe does four things.
- It indicates possession. Examples: The cat's eyes are green. The students' conduct was excellent.
- It indicates the omission of one or more letters. Examples: You're the one he chose. She plays rock 'n' roll.
- It indicates the omission of numbers. Example: They were in the class of '97, and
- An apostrophe is used to write plurals of a single letter. Example: His grades included three C's.
[Note: No. 4 also works for pluralizing abbreviations of two or more letters, like GI's, and decades, like the 1990's, although Harbrace 15c notes that, when no confusion would result, you can leave the apostrophe out of the examples above.]