For years, we have been trained to view web postings from our friends in a certain order. Refresh the top of your various “feeds” — the running column of content on some versions of Facebook, Twitter and Instagram — and you will see the latest news at the top. The further back you scroll, the older the material gets.

As our online networks of friends have grown larger and the social media companies have matured, the feeds have evolved. Facebook changed its news feed in 2009 by switching to an algorithm largely based on the popularity of posts, among other signals. Last month, Twitter introduced older, popular tweets to the top of users’ feeds, out of order, if the user had been away from the service for a time.

On Tuesday, Instagram joined that club. The photo-sharing service plans to begin testing an algorithm-based personalized feed for users, similar to one already used by its parent company, Facebook. That means it would shift away from the strictly reverse chronological order that the service has used since it began in 2010. Instead, Instagram will place the photos and videos it thinks you will most want to see from the people you follow toward the top of your feed, regardless of the time those posts were originally shared.

That could mean that if your best friend posted a photo of her new Bernese mountain dog’s puppies five hours ago while you were on a flight without Internet connectivity, Instagram might place that image at the top of your feed the next time you open the app. Based on your history of interaction with that friend, Instagram knows you probably would not want to miss that picture.