Today I'm going to talk about apostrophes. This is probably the most misused punctuation I see, and it is my personal pet peeve.

The primary use for apostrophes is to show ownership. 

the owner's car

the children's toys

The mistake I see most often is using an apostrophe to make a word plural:

the guy's

When a word ends with "s", there are two ways to use an apostrophe and both are correct:

Add "'s":

the boss's desk

Add an apostrophe:

the boss' desk

To make a plural word show ownership, simply add an apostrophe.

the guys' night out

Wrong: the guy's night out (this means their is only one guy)

The other use for an apostrophe is in a contraction. The apostrophe goes where the letter that is left out would go.

Doesn't NOT does'nt

I hope you enjoyed this post and let me know if you have any questions!