Arguably the biggest change they’ve made over the years was the addition of stories. However, even that feature, while copied from Snapchat, was still an extension of their core photo sharing behavior. And, ultimately, stories increased the value of feed-based photo sharing on Instagram as well. Before stories, all your daily selfies, food shots, workout updates and so on all went into your feed. Now, much of that lower quality posting goes into stories, and feed posts are reserved for higher quality photos, creating an enhanced feed experience.