We normally use -’s for people or animals :

The boy’s surname

The horse’s tail

The manager’s office’s

You can use -’s without a following noun :

This is not my house, it’s my siter’s (my sister’s house)

To make the possessive form of nouns in writing, we add ‘s to singular nouns and to irregular plurals that don’t end in -s:

John’s car

the women’s liberation movement

and add ‘ (an apostrophe) to regular plurals:

the boys’ football boots

the companies’ difficulties.

We can use the possessive form of nouns with people or groups of people (e.g. companies),

other living things, places, and times. To make the possessive form of names ending in

we can add either ‘ or ‘s:

• It’s Michael Jones’ (or Michael Jones’s) new computer.

Sometimes we add ‘s to the last word of a noun phrase, which may not be a noun:

• She’s the boy on the left’s sister.

«When we are talking about relationships between people we can also use a noun without’s:

An uncle of Mark’s, (or An uncle of Mark.)

The noun following a possessive form can be left out when we talk about someone’s home or some shops and services ( the chemist’s, the hairdresser’s,etc)

I must go to the butcher’s this morning. (= the butcher’s shop) (Notice that in cases like this we can also use the singular without’s: I must go to the butcher this morning.)

Often we can use the possessive ‘s or of + noun with very little difference in meaning:

Ireland’s beauty / the beauty of Ireland

However, sometimes we prefer to use the possessive form or the of form. In general, we are more likely to use the possessive ‘s form of a noun:

when the noun refers to a particular person or group of people

The children’ smiles

• when we are talking about time, as in:

next year’s holiday prices

last night’s TV programmes

Next week’s meeting has been delayed

In the same way you can say today’s/tomorow’s/this evening’s/thursday’s, etc.

For things, ideas, etc, we normally use of :

The window of the room

The name of the book

The owner of the restaurant

We normally use of (not noun+noun) with the beginin/end /top/bottom/front/back/midle/ side, etc.

The back of the car

The beginning of the year

You can usually use ‘s or of for an organisation (a group of people) :

The goverment’s decision or de decision of the goverment

It is also possible to use ‘s for places :

the town’s new cinema

Kaynak: www.englishpage.blogcu.com