But mostly you don't have to worry or do anything about it. The IP address given for your internet use is unique meaning no one else has it. But, you don't own the address. If you are not using it, it will be available to another user and when you need one again you may get a different address. All of this is handled in the background not requiring user intervention. There are ways to reset and get a new address. Some may prefer this for security reasons. link here