The possessive case indicates ownership and is shown by adding ‘s to a singular noun, by adding an apostrophe after the s in a plural noun, or by using a prepositional phrase.
A player’s experience is analysed using a new technique.
The players’ experiences are analysed using a new technique.
The graves of two women were found in the rich burial site at Oseberg.
Usually, an “‘s” is used when the owner is a person or a pet and “of” is used when the owner is a thing or an animal that is not a pet. There are exceptions to this rule, however.