You can transfer information and files between your iOS devices and computers, using iCloud or iTunes.
iCloud stores content such as music, photos, calendars, contacts, documents, and more, and wirelessly pushes it to your other iOS devices and computers, keeping everything up to date. See iCloud.
iTunes syncs music, video, photos, and more, between your computer and iPhone. Changes you make on one device are copied to the other when you sync. You can also use iTunes to sync files and documents. See Sync with iTunes.
You can use iCloud or iTunes, or both, depending on your needs. For example, you can use iCloud to automatically send the photos you take on iPhone to your other devices, and use iTunes to sync photo albums from your computer to iPhone.
Important: To avoid duplicates, sync contacts, calendars, and notes with iCloud or using iTunes, but not both.
You can also manually manage content from iTunes, in the device’s Summary pane. This lets you add songs and videos, by choosing a song, video, or playlist from your iTunes library and then dragging it to your iPhone in iTunes. This is useful if your iTunes library contains more items than can fit on your device.