Apostrophes in the English language are used to denote letters omitted or to denote possession. We use the apostrophe in writing contractions so that "do not" becomes "don't". The apostrophe after the "n" indicates that a letter is missing. In this case the letter is "o". Similarly, when we write abbreviations such as "ass't" for "assistant", the apostrophe again indicates that letters are omiitted. In this instance there are several letters, "istan", that are left out. The apostrophe is also used to note possession, or ownership. In singular possessive nouns, the apostrophe is put before the "s" usually, as in "girl's" such as might be found in this sentence: The girl's dress was blue. In plural possessive nouns, for nouns that form their plural by adding "s" or "es", the apostrophe comes after the "s" as in the word "girls'" in the following sentence: The girls' dresses were blue. In nouns that form their plurals in an irregular way, such as "woman" that becomes "women" when pluralized, the apostrophe comes before the "s" as in "women's" such as in this sentence: The women's dresses were blue.