Considering how many ways the apostrophe can be employed, erroneous use of that punctuation mark is widespread.
Here are brief discussions of 10 categories of apostrophe abuse (including one writers and editors must let stand, even though it may pain them to do so).
Writing the plural form of a noun in which an apostrophe precedes the plural s, such as when taxi’s is written instead if taxis, is a common error. (This mistake is known as a greengrocer’s apostrophe due to its ubiquity in handwritten—and even printed—store signs.)
Pronouns are followed by an apostrophe and s only as contractions (for example, he’s). Possessive pronouns (such as theirs and yours) never include an apostrophe. The possessive pronoun its does not take a pronoun; the contraction it’s (meaning it is) does.
3. Separate/shared possession