Patches are another word for updates. Whenever Electronic Arts releases a patch/update, you'll be notified via your Sims 3 launcher if you've registered your game at the Sims 3 website. When you go through the uninstall and reinstall process, you will automatically be prompted to download the current patch/update before it will let you continue with the installation. It's a good idea to keep your game updated in this fashion because it often fixes bugs and glitches, and sometimes even introduces new interesting things to the game. Also, if you choose to participate in our Challenge Tournament, it's required that you be updated to the latest patch.