How to clear the Photos icon badge

For some reason that is not clear to me, the Photos app icon on the dock of my Yosemite OS now displays a badge (the number 1 in a red circle top right corner)

First of all, I have no idea what that badge is suppose to represent. Second, when I launch the app I have not idea what the thing is that I'm suppose to look at, acknowledge or in some way "touch" so that the badge goes away.

Solution 1:

If you haven't already, turn on the sidebar - Option-Command-S - then look towards the top and under Shared, click Activity. Likely there is some activity on a shared album or Photo Stream. It may also be someone inviting you to join a shared album or Photo Stream. (I'm not sure how that would show up in Photos, as I haven't had any invitations since Photos was released.)

Either way I'm guessing once you take a look at that area, the badge will disappear.

Solution 2:

Supposing you're talking about iOS, the badge may mean somebody commented or liked one of your photos on a shared folder.