Many non-native as well as native English speakers find possessives in English grammar confusing. That pesky little apostrophe can cause a lot of problems! This is even more the case when a word is in the plural form. Let's look at the rules for using possessives.

Most singular nouns can be transformed into the possessive form by adding an apostrophe and an "s":

John's book
The cat's food
Jane Austen's novels
A good night's sleep

If the noun happens to end in an "s" before the possessive is formed, such as in names, there are two ways of using the apostrophe:

Charles' book OR Charles's book
Dickens' novels OR Dickens's novels

Consistency is the key here as either way is correct, but you should not interchange them in the same piece of writing. Many people prefer placing only an apostrophe after the "s" simply because they feel it looks better.

When it comes to the name of holidays, it can also be confusing as to whether you need to use the singular or plural possessive:

Mother's Day
Mothers' Day

And there might be confusion as to whether to use an apostrophe at all, as in "Mothers Day". Actually, there is no right or wrong answer here as whether or not you use an apostrophe is based on your perception. For example, if you think that each mother "owns" the day, then you would write "Mother's Day". If you think they are a group you would write "Mothers' Day" and if you see the words as a plural adjective, you would choose "Mothers Day". Remember that consistency is the key; pick one form and stick with it in your text.

Another confusion that can arise regarding the possessive form is the word "children". Children is not a regular plural - you cannot make it plural by adding an "s" or "es" on the end (childrens), as it is already the plural of "child". When you use the possessive form for "children" you must add an apostrophe followed by an "s" - children's.

This example is the same for all irregular plurals, such as "women" (women's), "geese" (geese's) etc. However, with words that do not change their form when they are pluralized, you will have to add an "s" or "es":

The algae were damaged by the fishes' overfeeding.

Sometimes, two or more nouns are involved in the possessive form. We can use people as an example:

John and Jane together own two cars. Therefore they are John and Jane's cars.

Notice that only "Jane" is given the possessive form. This is because both John and Jane possess the same cars, they share that possession and therefore the possession belongs to the whole phrase, not just Jane.

However, we can also write:

John's and Jane's cars. In this phrase their possession is separate and that is why they are each given an apostrophe and an "s" to show they each own cars and do not share ownership of their cars.

As you can see, there is some confusion surrounding possessive forms, but with a little practice it becomes much easier to construct possessives in your writing.

KJ Hutchings is the owner of KJ Language Services, providing proofreading, editing and writing services to businesses and students, in particular those who use English as a second language. For more information, visit her site at: http://www.kjlanguageservices.com/