We use the possessive S to refer to a noun that belongs to somebody. The possessive S of course is about possession and ownership. Observe these examples of how it words.
In English we do not tend to use …
of someone. We use an S at the end of the name of the person, or better said, the person´s name; because the name belongs to the person.
Observe these examples:
It is Daniel´s bike. Not it is the bike of Daniel.
They are Wendy´s glasses. Means, the glasses are Wendy´s`.
It is the doctor´s bag. Means, the doctos owns the bag.