When to put an aphostophy?

An apostrophe is used to indicate possession, to form contractions, and to pluralize certain lowercase letters. For possession, it typically follows the noun (e.g., "the dog's bone" for one dog or "the dogs' park" for multiple dogs). In contractions, it replaces omitted letters (e.g., "don't" for "do not"). Use it sparingly for plurals of lowercase letters, like "mind your p's and q's."