Instagram uses Machine Learning to customize what shows up on your Feed. The Explore Page also works in a similar manner.
There are six factors that Instagram uses to decide what content is shown.
Interest: The order of videos and photos on your Feed depends on how likely you will be interested in the content. Instagram analyzes your past activities to gauge your interest.
Timeliness: Instagram shows you the posts that are the most recent and, therefore, the most relevant.
Relationship: Instagram does not want you to miss posts from those you are the closest to, such as family and friends. Instagram analyzes your past interactions to see which accounts you engage with the most and ranks them accordingly.
Frequency: How often you open Instagram will also impact the content that you see. For instance, if you open Instagram just once a day, you will see posts that are the most relevant for the day. If you open Instagram every hour, you will see the most relevant content that you haven’t seen before.
Following: Users who follow hundreds of accounts may see less from the individual accounts. However, those who only follow a few accounts see more from their friends or closest accounts.
Usage: Whether you spend long hours on Instagram or just browse through in short bursts also determines what you see on your Feed. For short visits, Instagram may only show relevant content, whereas, for others, it may show a larger catalog of content to browse through.