The little apostrophe can make a big difference in meaning. The following sign at a neighborhood swimming pool, for instance, says something different from what the writer probably intended:
Please deposit your garbage (and your guests) in the trash receptacles before leaving the pool area.
The sign indicates that guests should be put in the trash. Adding a single apostrophe would offer a more neighborly statement: Please deposit your garbage (and your guests’) in the trash receptacles before leaving the pool area asks that the guests’ garbage, not the guests themselves, be thrown away.
AT A GLANCE