Instagram introduced a feature Tuesday that lets its 500 million monthly users publish photo and video slideshows that disappear after 24 hours, adopting the defining format of rival Snapchat inside one of the world’s largest social networks. “Stories” places a row of profile pictures above the main feed, giving ephemeral posts the most prominent position in the application.

Users can add text and drawings, move forward or backward through a sequence and see who viewed each item. Stories do not appear on a profile grid or in the regular feed, and they receive no public likes or comments. The company’s official announcement says the feature is intended to let people share ordinary moments without worrying that they are posting too often or disrupting a carefully curated profile.

A direct adoption of Snapchat’s signature product

The resemblance is unmistakable. Snapchat introduced its own Stories in 2013, organizing photos and videos into a chronological collection available for one day. Instagram uses the same name, lifespan and basic interaction pattern. Chief Executive Kevin Systrom did not deny the source, telling TechCrunch that Snapchat “deserves all the credit” for developing the format.

Systrom argued that the relevant question is how a successful format works inside a different network. Instagram’s social graph is built largely around public following and polished posts; Snapchat grew from private messaging among close friends. By placing Stories above the existing Instagram feed, Facebook’s photo-sharing unit can offer casual sharing without asking users to reconstruct an audience in a separate application.

The Washington Post’s product walkthrough documented the parallels and the few interface distinctions. Instagram viewers tap the right or left side of the screen to move within a story and swipe to the next account. Replies become private Direct messages, while account privacy settings determine who can watch.

Scale changes the competitive equation

Instagram reported in June that it has more than 500 million monthly users and 300 million daily users. More than 80 percent live outside the United States, and the service receives about 95 million new photos and videos each day. Time’s June interview with Systrom described accelerating growth and a 150 percent increase in time spent watching video.

Snapchat, by comparison, has roughly 150 million daily users and is especially strong among teenagers and young adults. Its advantage lies in habit, intimacy and a camera-first design rather than total reach. Instagram’s advantage is immediate distribution: hundreds of millions of people will see Stories in an application they already open.

MediaPost’s launch report said Instagram users produce 4.2 billion likes per day, evidence of an engagement system built around permanent posts. Stories offers a second mode that may increase frequency without flooding that system. The company is effectively separating polished identity from everyday narration.

From the feed to a new publishing layer

The main Instagram feed has become increasingly selective. Users often post only their best images, and the company recently shifted from a strictly chronological order to an algorithmic ranking. Both changes can raise the perceived stakes of each post. A 24-hour format lowers those stakes because content is temporary and displayed outside the grid.

The launch also gives Instagram a new surface for video. Stories can string together short clips and images in a full-screen sequence, a form better suited to events and daily updates than a single square post. TechCrunch’s account of the rollout emphasized that the feature addresses “imperfect sharing”—material people may hesitate to place permanently before a broad audience.

At launch, Stories contains no advertising and offers brands the same organic tools as other accounts. But a prominent, full-screen format could eventually become valuable inventory. Facebook has sophisticated advertising systems and relationships with millions of businesses; adding commercial messages would be technically straightforward if users accept the product.

Copying as platform strategy

Technology companies routinely adopt rivals’ successful features, but the closeness of this imitation is unusual. Facebook previously created Poke and Slingshot, standalone apps with disappearing messages, neither of which displaced Snapchat. Integrating the behavior into Instagram avoids the central weakness of those experiments: persuading users to install another service and find friends there.

Time’s launch analysis noted that Facebook reportedly offered $3 billion for Snapchat in 2013. Snapchat rejected the approach and has since raised capital at a much higher valuation. Instagram Stories is therefore a product response to a competitor Facebook could not buy.

The move raises questions about whether dominant networks can reduce a challenger’s differentiation simply by copying its interface. Snapchat retains distinctive private messaging, filters, lenses and Discover media channels, and its culture may not transfer easily. But Instagram can expose the Stories concept to a larger and more global audience, making the format a general expectation rather than a feature associated with one company.

Privacy, control and the meaning of disappearance

Stories vanish from public view after 24 hours, but temporary presentation is not the same as guaranteed deletion from every system. Viewers can capture screens, and services may retain data under their policies. Users must still decide whether a fleeting interface changes the risk of sharing sensitive material.

Instagram allows people to hide a story from selected followers and, for private accounts, limits viewing to approved followers. The company also applies its existing community standards and reporting mechanisms. Those controls are important because the feature encourages more frequent and less considered posting.

Wired’s contemporaneous assessment argued that borrowing interface conventions is common in technology and can benefit users, while acknowledging the unusually direct copy. The competitive effect will depend less on novelty than on whether people prefer Instagram’s established network or Snapchat’s more intimate one.

Stories begins rolling out globally on Apple and Android devices this week. Its immediate achievement is architectural: Instagram has inserted a second social product above the first, one designed for impermanence rather than permanence. If users adopt it, the shift could change not only the contest with Snapchat but also what people expect to share on Instagram at all.