Does an apostrophe come after the letter s?

That depends on what you would like to say. If the Word is a plural possessive, the apostrophe goes after (e.g. girls'). Example sentence: That was the girls' ball. This means that the ball belongs to a group of girls, and not just to one girl. If the ball belongs to one girl only, it would be written: That was the girl's ball. If you intend to make a simple noun plural, the apostrophe is not used. Many people make the simple mistake of using apostrophe s to make simple nouns plural. This is notcorrect: Her cat's are out of control. The writer's intention is to say that the person has several cats (more than one) and that they are out of control. The sentence should be: Her cats are out of control. This is not correct: The cats paw's have extra claw's. The writer's intention is to write about one cat, not several. The paws are possessed by the cat, and the Word cat's will convey that. The writer is talking about several paws, and several claws. The Words paws and claws will convey that. The sentence should be: The cat's paws have extra claws.