The main purpose of Instagram is to be a social media platform where users can share photos and videos with their followers. It allows users to take photos or videos, apply filters or other effects, and then share the content on their profile. Users can also view and like posts from other users, and follow their favorite accounts. Instagram also has messaging features, the ability to search for content and hashtags, and offers a platform for businesses and influencers to promote their products and services to a large audience.