The three-letter code on your baggage tag tells the baggage handlers which airport your luggage is going to.
Millions of bags are correctly checked in every day, using this system. But an error could send your luggage to a distant destination and cause you a lot of inconvenience. It’s quick and easy to check the codes on your bag to make sure they are correct. To verify that the tags are right, look right on your ticket. Your ticket always displays the 3-letter code of your destination airport. Match the three-letter code to the one on your baggage tag. That's all there is to it.
After your flight and before you fly again, be sure to strip any old tags from your luggage. To avoid any confusion for baggage handlers, there should be only one tag on your luggage—the one coded for your next destination.