For some of us, grade-school grammar lessons haven't stuck. I managed fairly well with my trusty Elements of Style until pretty recently, but the ongoing assault on grammar that is the Internet occasionally shakes my confidence.

(Every time I want to type rein, rain, or reign, for example, I need to close my eyes and meditate for a moment.)
If you're one of those people for whom grammar and punctuation don't come easily (or aren't a native English speaker), this handy flowchart from GrammarCheck.net will come in handy: It will help you navigate all the questions that determine whether you need an apostrophe or not, from the big (Are you making something possessive?) to the small (Is it a single-letter word?).

Now, confession: I love reading grammar guides not only because I'm a total geek, but because I often either learn something I don't know or the explanation articulates a concept I understand intuitively but never really thought about: For example, one-letter words in sentences like "There are two t's in kittens" take an apostrophe.

One quibble: In the "Are you making a contraction?" section, the question reads "Are you making words shorter by replacing some of its letters with an apostrophe?" This is sloppy - it should read "Are you making words shorter by replacing some of their letters with an apostrophe?" Perhaps the next GrammarCheck flowchart should be on the sticky grammar question of agreement.

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