Apostrophes used incorrectly for plurals

Don't Add Your Own Apostrophe to a Plural Word

In English, the plural form of a word is most commonly shown by adding an s to the end (e.g., cats, pictures). You must not add your own apostrophe!

In other words, do not add 's to the end. Just add s.

The plural forms of words ending in vowels (e.g., video, patio) are extremely prone to this error. Forming a plural by adding's is a common mistake, and it is considered a grammatical howler. 

Examples:

• Dog's look up to us, and cat's look down on us. I prefer pig's — they treat us as equal's.  (badly transcribed version of a Sir Winston Churchill quote)
• Anteater's prefer termite's to ant's. 
• Pearl's melt in vinegar. 
• Rent two video's for the price of one. 
• Three large male lion's approached the 4x4. 
(lions )
• Snow White and the Seven Dwarf's. 
(Dwarfs )
(Actually, you could write "Dwarves" too — both are correct plurals of dwarf.)

(camera's  cameras )
(motorway sign)


(Minister's are very...  Ministers are very... )
(Letter from a former British Minister for Education) 

• Their board genuinely stated: "Open seven day's a week and weekend's". 
(days  / weekends  )
• She fly's to New York regularly. 
(flies )

When to Use Apostrophes

The rules on using apostrophes can be summarized:

• To replace missing letters

aren't
isn't
can't

• To show possession

Sarah's jumper
The dog's toy
The dogs' kennel

• In temporal (or time) expressions

3 months' wages
A day's leave
2 days' notice

• To show the plural of an awkward abbreviation, letter or number

BUY THREE CD'S.
Mind your p's and q's.
Your 5's look like 6's.