Usually an apostophe indicates a contraction - where the missing letters should be. By extension this may also apply to possessives. (+"has"?) The " 's " is what indicates the possessive; not only the apostrophe. I hope you can check these sites OK! :) http://www.angryflower.com/aposter.html http://theoatmeal.com/comics/apostrophe And about never using an apostrophe for plurals: http://www.angryflower.com/plural.gif

An apostrophe can denote either ownership or a contraction. An ownership example would be: My computer = Jamie's computer. A contraction example would be: My computer is not working = My computer isn't working. You should beware that in the English-speaking world, many people seem to think that the apostrophe is used to denote the plural, and examples of this can be seen on a daily basis. This is incorrect.