The Snake begins to eat it's tail

[Urbane Guerrilla]

Originally Posted by TheMercenary

Yea, I always screw that up thinking it is to show possession, when that should be reserved for nouns and pronouns. My bad.

Possessive Apostrophe S: Nouns do. Possessive pronouns don't. So as not to get mixed up with contractions. The rule isn't even arbitrary; it's got a reason.

So ambiguity only pops up with a contraction constructed on a noun -- and you resort to context to determine meaning.

One should always keep a copy of Strunk & White near to hand. Despite its decretal tone, which can irritate a little, only one or two of its usage ukases have obsolesced since it was written for the help of incoming freshmen in the nineteen-twenties.