You don’t always need to write flawless English.

Some grammar rules are optional. Others make you look dumb.

Poor grammar undermines your message. Readers will question your intelligence and professionalism. Clumsy English can stick around for a long time warning the world not to take you seriously.

Apostrophes are a danger zone for inexperienced writers. If you are not a confident writer, alarm bells should ring every time you hit the apostrophe key.

Five apostrophe errors to watch for:

1. The greengrocers’ apostrophe gets its name because handwritten shop signs often use apostrophes incorrectly. It’s unfair to single out greengrocers — the mistake is everywhere.

A greengrocers’ apostrophe happens when a writer turns a word into a plural with an apostrophe s instead of the correct plural ending.

For example: Macintoshes and PCs not Macintosh’s and PC’s.

2. It’s when you mean its.

Its is a possessive pronoun — like his or her. It’s is a compact way of writing “it is” or “it has”.

If this bothers you, make a point of writing it is out in full and never writing it’s. Alternatively try speaking the sentence and checking whether replacing its with “it is” makes sense.

And while we are on the subject, there is no such word as its’.

3. Confusing your with you’re. Your is another possessive pronoun. To check think of: his computer, her computer, its computer, your computer.

You’re is a contraction of “you are”, as in “you’re reading a column on basic grammatical errors”.

4. Muddling they’re, their and there. Another common apostrophe problem comes with “they’re” which is a shortened version of “they are”. Their is the possessive plural pronoun. As in; his computer, its computer, your computer, their computer. There is a place. It is the opposite of here. Their and there are particularly easy words to confuse when typing on a keyboard.

5. When to use who’s and whose. Another case of a possessive pronoun that doesn’t have an apostrophe being confused with a verb contraction. Think of: whose computer is that? Who’s using it?