a. The ending 's
One way in which English nouns indicate possession is by means of the ending 's.
e.g. the boy's hat
Sally's bicycle
In the above examples, the ending 's indicates that the hat is possessed by the boy, and that the bicycle is possessed by Sally. The English ending 's is related to the German possessive ending es.
The ending 's is most often used with nouns referring to human beings or animals.
e.g. the child's toy
the bird's song
Nouns formed from two or more words joined by hyphens indicate possession by adding 's to the last word.
e.g. the runner-up's score
the sister-in-law's children
The ending 's may also used with nouns referring to non-living things which are sometimes thought of as if they were living, such as ships, countries, corporations, and the earth.
e.g. the ship's bell
Italy's exports
the city's parks
the earth's surface
The ending 's may also be used with nouns referring to units of time.
e.g. a day's work
a week's delay
In addition, the ending 's is used with nouns referring to non-living things in a few idioms such as the following:
e.g. a stone's throw away
your money's worth
It should be noted that the ending 's is used only with singular and plural nouns which do not end in s.
e.g. the 's hat
the children's books
the men's jackets
b. The ending s'
For plural nouns which end in s, the ending 's is not used. Instead, an apostrophe: ' is placed after the s which indicates a plural. The following examples illustrate how the plural nouns students and Smiths indicate possession.
e.g. the students' books
the Smiths' house
In these examples, the apostrophes indicate that the books belong to the students, and that the house belongs to the Smiths.
It should be noted that both 's and s' are pronounced like s. Thus, in spoken English, there is no distinction between a singular noun with the ending 's and a plural noun ending in s'. For instance, the phrase the student's books is pronounced in the same way as the phrase the students' books.
In American English, singular nouns ending in s can also indicate possession by means of a final apostrophe.
e.g. James' scarf
Dickens' novels
In these examples, a final apostrophe is used with the singular proper nouns James and Dickens to indicate possession.