Instagram feed algorithm

Instagram is self-identifies as:
"Instagram is a fun and quirky way to share your life with friends through a series of pictures. Snap a photo with your mobile phone, then choose a filter to transform the image into memory to keep around forever. We're building Instagram to allow you to experience moments in your friends' lives through pictures as they happen. We imagine the world more connected through photos."

Algorithm Change
Recently, this summer Instagram spurred a controversy over how users view photographs. Rather, than images appearing in the order, they were posted a user will now see "posts you're likely to care about most will appear higher in your feed." These deeply upset many users, as many of their posts, were no longer receiving the same attention they were before.