Shared photo albums in iCloud can be a very handy way to pass photos around with friends and family members, since anybody with an iPhone, iPad, or iPod touch and an iCloud account already has everything they need to receive updates without needing to worry about chasing web links or installing other apps. The way Apple has set these up is especially handy if you’ve got an album you’re contributing to an an ongoing basis, as any new photos you add are pushed to everybody else the album is shared with.
Since iCloud Photo Sharing is part of the iOS Photos app, you may think that’s the only place you can share photos from, but that’s actually not the case—you can send a photo to iCloud Photo Sharing from any app that supports the iOS 8 sharing sheet. Just bring up the normal sharing options, and if “iCloud Photo Sharing” doesn’t already appear, scroll to the right, tap the “More” button and turn it on from the list of options. You can even reorder it by dragging it up higher on the list. Once enabled, you can easily share to an iCloud Shared Photo album from whatever photo app you’re in — even something like Dropbox, Google Photos, or Lightroom Mobile, making it easy to still take advantage of iCloud Photos even if your photos aren’t stored in the iOS Photos app.