Users can upload photographs and short videos, follow other users' feeds, and geotag images with the name of a location. Users can set their account as "private", thereby requiring that they approve any new follower requests. Users can connect their Instagram account to other social networking sites, enabling them to share uploaded photos to those sites. In September 2011, a new version of the app included new and live filters, instant tilt–shift, high-resolution photographs, optional borders, one-click rotation, and an updated icon. Photos were initially restricted to a square, 1:1 aspect ratio; since August 2015, the app supports portrait and widescreen aspect ratios as well. Users could formerly view a map of a user's geotagged photos. The feature was removed in September 2016, citing low usage.

Since December 2016, posts can be "saved" into a private area of the app. The feature was updated in April 2017 to let users organize saved posts into named collections. Users can also "archive" their posts in a private storage area, out of visibility for the public and other users. The move was seen as a way to prevent users from deleting photos that don't garner a desired number of "likes" or are deemed boring, but also as a way to limit the "emergent behavior" of deleting photos, which deprives the service of content. In August, Instagram announced that it would start organizing comments into threads, letting users more easily interact with replies.

Since February 2017, up to ten pictures or videos can be included in a single post, with the content appearing as a swipeable carousel. The feature originally limited photos to the square format, but received an update in August to enable portrait and landscape photos instead.

In April 2018, Instagram launched its version of a portrait mode called "focus mode", which gently blurs the background of a photo or video while keeping the subject in focus when selected. In November, Instagram began to support Alt text to add descriptions of photos for the visually impaired. They are either generated automatically using object recognition (using existing Facebook technology) or manually specified by the uploader.

On March 1, 2021, Instagram launched a new feature named Instagram Live Rooms, which lets four people go live together.

In May 2021, Instagram announced a new accessibility feature for videos on Instagram Reels and Stories to allow creators to place closed captions on their content.