When you jailbreak an ipod touch, you allow third party applications to be accesible on it, such as cydia and installer, which is no longer available. Third party applications are normally free and allow you to do stuff that a normal ipod touch would not allow you to do, such as customize your icons, apps, home screen and much, much more! But there are some catches however. There is a very small possibility that when you attempt to have your ipod touch jail broken that it will freeze up and no longer be of use. You’ll basically have a big piece of plastic that you wasted 200$ on. So beware of that . Also, when you attempt to jailbreak your ipod touch, you automatically void your warranty. So if your ipod touch breaks for any reason, your ipod warranty will not cover it. Hope I helped.