APOSTROPHES IN POSSESSIVES
Squeek touched on part of this, but the rest is not the most well-understood of subjects, so mistakes of this kind are often overlooked. I'll try to clear some of this up.
Case 1:
Singular possessives that do not end in 's'. Everyone knows how to do these. Add an apostrophe and 's', e.g. "chair's legs", "Mary's face", etc.
Case 2:
Plural possessives that do not end in 's'. Like with singular nouns, these are often quite obvious. "The children's homework," "the deer's meat," and "the feet's smell" are all examples.
Case 3:
Singular possessives that end in 's'. Unlike with plural possessives, these WILL NOT terminate in an apostrophe simply because they are singular. "Chris's hand," "Tyler Jones's room," or "my boss's job" all end with an apostrophe and 's' just like the other singular possessives.
Case 4:
Plural possessives that end in 's'. With these nouns is the ONLY time (save for the two exceptions that will be noted below) that a word terminates in an apostrophe. Examples: "The Millers' house," "the students' homework," and "the rabbits' down." Also note that regardless of the structure, surnames will take the apostrophe after the pluralization. This can look especially awkward with -es names such as with Jones, but the dog belonging to the entire family is still "the Joneses' dog."
Case 5:
Exceptions.
- Obviously, as Squeek has said, "its" is what you should use to denote something belonging to whatever "it" is. It is a singular possessive that does not take an apostrophe, so it is an exception to Case 1.
- Moses and Jesus. These are the only two singular possessive nouns that terminate in an apostrophe. For some reason, philologists saw fit to let these two figures be special, so don't flip out if you read about "Moses' staff" or "Jesus' word," because they are completely fine.
That's all for now. I think I'm going to have fun writing these.
--Guido
http://andy.mikee385.com