Instagram is about to start carrying adverts, in a move which could test user's loyalty to the popular photography and video sharing app.
The company says users in the United States will start seeing a "sample" advert in the coming week.
"This is a one-time ad from the Instagram team that's meant to give you a sense for the look and feel of the ads you will see," the company said in a blogpost on Friday.
The advert will carry a "sponsored" label in the top right hand corner and users will be able to make the image disappear by tapping the "..." symbol in the bottom right hand corner.
After the sample advert, Instagram said it will begin carrying commercials from a "handful" of brands, including Adidas, Ben & Jerry's, Burberry, General Electric, Lexus, Levi's, Macy's Michael Kors, PayPal and Starwood.
The company was unable to confirm when users outside the US will start seeing adverts.
Much may depend on the reaction in the US, with Instagram indicating it is keen to hear feedback.
The introduction of adverts is a delicate and potentially risky move for any social media app or website.
The risk is that users can become annoyed if adverts start cluttering a site and move on to a rival.
There's also a danger that a website's inherent 'cool' can be lessened by allowing brands to target users.
Instagram director of business operations, Emily White, acknowledged those fears in comments made to the Wall Street Journal earlier this year.
"If people see super spammy ads in their feeds it's going to be destructive," she said.
However, Instagram's intention appears to be to run creative adverts that users may even enjoy seeing alongside others' photographs and videos.
The company has been under increasing pressure to carry adverts, and generate greater revenue, since being bought by publicly-listed Facebook last year for about US$1 billion.
Instagram confirmed all users would retain ownership of photos and videos they publish.
It said adverts would be targeted to users' interests.
"And to do that we will use information about what you do on Instagram and Facebook (our parent company)," it added.