Both the iPhone and the iPad are equipped with multimedia playback through their built-in iPod applications. Music downloaded from the online iTunes Store is linked to the account that was used to purchase it. By signing the iPhone, iPod and iTunes multimedia management software on your computer into the same account, all devices can be synchronized to share and transfer content among them.
Launch the Settings application on the iPhone by tapping its icon on the home screen. Open the "Store" page and take note of the iTunes account the iPhone is currently using.
Launch the Settings application on the iPad, and open the "Store" page. Enter the same username and password for the iTunes account being used by the iPhone, and then tap the "Sign In" button. The iPad is now linked to the same iTunes account as the iPhone.
Download and install the latest version of iTunes on your computer, following the installation instructions detailed on the Apple web site. Once installation has completed, launch iTunes on the computer.
Click the "Store" menu at the top of the iTunes window and select "Authorize this computer." Enter the same iTunes username and password used on the iPhone and iPad, and then click the "Authorize" button. This grants the computer access to the iPhone's and iPad's iTunes account.
Click the "Store" menu in the iTunes window and select "Sign in." Enter the iTunes account details again, and then click the "Sign In" button. This fully links the computer to the iTunes account.
Connect the iPhone to the computer using its USB cable. The iTunes software will automatically detect that the iPhone has been connected. Open the "Music" tab in the main iTunes window and check the "Sync Music" box. Click the "Sync" button in the lower-right corner of the iTunes window, and the iPhone's music content will be transferred and backed up onto the computer. Disconnect the iPhone once synchronization has completed.
Connect the iPad to the computer using the USB cable. Open the "Music" tab in the main iTunes window, and check the "Sync Music" box. Click the "Sync" button in the lower-right corner of the iTunes window, and the music backed up from the iPhone will be transferred to the iPad.
Things You'll Need
iPhone/iPad USB cable
The music will also be available to listen to on the computer through iTunes. Any additional content downloaded on the iPhone, iPad or on the computer through iTunes will be transferred to all other devices on the same account whenever you perform a synchronization.
If you sign a device out of the iTunes account, its previous content will be removed.