Photo Stream

The way that Photo Stream works is really simple. First, you take some pictures using your iOS device. Then, these pictures are automatically uploaded to the iCloud server. Other devices that have Photo Stream enabled receive these pictures immediately. Photo Stream only stores pictures that are taken using the Camera app on iOS devices.

Of course, your devices need to be connected to the Internet via cellular data or Wi-Fi. For those who use Wi-Fi-only iOS devices, such as iPod touch and iPad with Wi-Fi, pictures are uploaded later when it's connected to Internet.

Photo Stream lets you upload unlimited pictures and it won't count on iCloud storage, but these are stored in Photo Stream for 30 days. After that, your pictures are automatically deleted. Make sure that you have stored all pictures on your Mac or PC so that you don't lose any. All pictures are uploaded in full resolution, but when they are downloaded to iOS devices, the resolution is reduced and optimized for the devices...