In general, you should update your phone or tablet, especially on Android-powered devices, where it could be security updates (Android has viruses, after all). iOS is the operating system for Apple's iPad and iPhone, and the operating system for the iPod Touch. If you have an Android tablet or phone (pretty much anything else), you should always download the latest updates. As for iDevices (iPad or iPhone or iPod Touch), as I don't have one, so I don't know if you should. Still, if you have an Android tablet or phone, you should always use the latest version of Android, as it won't let you update if your device isn't compatible (and sometimes it won't let you even if it is, as it is up to the company that made your device to send out the update to all copies of the device you are using (they don't need to do it per-copy, but they do need to do it for the device in general)), so you don't even need to worry about lack of compatibility, and newer versions of Android are way better than older versions, as they are more stable, more secure, and sometimes they just plain look better on top of stability and security .