What is the difference between the words client's, clients, and clients'?
At a meeting of the representatives of that professional's clients, one client's displeasure with his services sequenced into an escalating debate amongst all of his clients' representatives.
All three words are used in the sentence above to contrast their application.
clients [plural] refers to a group of people who do business with a professional.
client's [singular possessive] is used to show possession of an item or thought (displeasure) belonging to only one client.
clients' [plural possessive] is used to show possession of items or thoughts (representatives) belonging to more than one client.