The apostrophe is a difficult mark to pin down. Many people find it impossible to know where exactly to place it in a word. They simply wedge it in somewhere and hope for the best. Their text becomes festooned with apostrophes, particularly when words end in S. No wonder there are websites and Facebook groups devoted to gathering photographic evidence of apostrophic errors.

An apostrophe indicates that something belongs to someone or something, or has a relationship with it. This can be something concrete, like Mary’s coat, or abstract, like Mary’s happiness. It is also used to indicate that a letter has been left out, such as didn’t for did not. Ask yourself if the word you want to spell falls into these two categories. If it doesn’t, leave out the apostrophe.
Here are three instances when an apostrophe should never be used.
Its/It’s
The confusion between its and it’s is the most famous example of an apostrophic error. I’ve said that an apostrophe is used to indicate possession, but its is the exception. You use its to show that something is belonging to or associated with an object, an organisation or an animal: its habitat, its website, its colour. The apostrophe in it’s indicates that a letter has been left out, in this case an i, because it’s is short for it is.
For plurals
A lot of plural forms of words in the English language end in S. For example, boy becomes boys and book becomes books. Some people seem to believe that apostrophes are used to denote that a word is plural, so they will put it in before the s. But unless you are referring to something that belongs to more than one person i.e. the boys’ books, you never use an apostrophe for plurals.
Verb Forms Ending in S
A lot of verb forms in English end in S, particularly in the third person present tense i.e. he goes, she cooks. Some people believe that because these verb forms end in S, they need an apostrophe, so they write he goe’s or she cook’s. Apostrophes have no link to verbs, or action words, whatsoever. Ask yourself if the word you’re spelling describes an action. If it does, don’t use an apostrophe.
Have you come across any interesting apostrophic errors? What aspects of the apostrophe do you yourself struggle with?