“Three main factors determine what you see in your Instagram feed:

  • Interest: How much Instagram predicts you’ll care about a post, with higher ranking for what matters to you, determined by past behavior on similar content and potentially machine vision analyzing the actual content of the post.
  • Recency: How recently the post was shared, with prioritization for timely posts over weeks-old ones.
  • Relationship: How close you are to the person who shared it, with higher ranking for people you’ve interacted with a lot in the past on Instagram, such as by commenting on their posts or being tagged together in photos.

Beyond those core factors, three additional signals that influence rankings are:

  • Frequency: How often you open Instagram, as it will try to show you the best posts since your last visit.
  • Following: If you follow a lot of people, Instagram will be picking from a wider breadth of authors so you might see less of any specific person.
  • Usage: How long you spend on Instagram determines if you’re just seeing the best posts during short sessions, or it’s digging deeper into its catalog if you spend more total time browsing”.

Source : How Instagram’s algorithm works | TechCrunch