Last month’s rule? Apostrophes are NEVER ever used to denote plurals.
This month’s? Apostrophes are used to denote possession.
For example:
- the dog’s bone
- the company’s logo
- John’s bakery
If there are two or more dogs, companies or Johns, the apostrophe comes after the ‘s’.
- the dogs’ bones
- the companies’ logos
- Johns’ bakery (An unlikely example, this bakery is owned by two friends called John!)
But, there is no apostrophe in ours, yours or hers.
Neither is there an apostrophe in ‘its’ when it is (it’s) showing possession.
- The bone is in its mouth.
Hopefully, this month we’ve managed to avoid our own ‘deliberate’ mistakes.