PhotoStream is Apple's cloud-based photo sharing service. It allows sharing of photos between different devices. These photos can be easily viewed on an iPad, iPod Touch, iPhone or Apple TV as well as on Macs and Windows-based PCs. You can turn on any of these devices and the latest uploaded photos can automatically be shared with any device in your account that has Photo Stream turned on. This implies that you do not have download photos from your iPad or iPhone. If both devices have Photo Stream, the photos are shared automatically.