Apostrophe S ( ...'s)

We normally use 's when the first noun is a person or an animal:

example:

• Mrs. Deborah's daughter
• the manager's office (not 'the office of the manager)
• the cat's fur

Otherwise (with things) we normally use ... of ...

example:

• the book's title or the title of the book

But it is safer and more usual to use ... of ...