[count] the punctuation mark used to show that letters or numbers are missing (as when did and not are combined into didn't or when the date 1776 is written as '76)

the punctuation mark used to show the possessive form of a noun (as in Lee's book or the tree's leaves)

the punctuation mark used to show the plural forms of letters or numbers (as in dot your i's and cross your t's or in the 1960's)