Instagram Will Begin Showing Ads in the Photo Stream.

You knew it had to happen eventually: Instagram is getting ads.

Facebook, which owns the fast-growing photo and video sharing service, warned Instagram users three weeks ago that photo and video ads were going to start showing up in their image streams. On Thursday, Instagram said the ads would start in the next week for users in the United States. (Foreign users will see ads eventually, but the company declined to be more specific.)

Much like ads in the news feed of Facebook, the ads will look like normal Instagram photos or videos but will be prominently labeled with the word “Sponsored” at the top. The company said early advertisers include Adidas, Ben & Jerry’s, Burberry, General Electric, Levi’s, Lexus, Macy’s, Michael Kors, PayPal and Starwood.

Although users won’t be able to opt out of seeing ads on Instagram, which is free, they can hide ads they don’t like and tell Instagram why they didn’t like them. “This will help us show you more interesting ads in the future,” the company wrote in a blog post announcing the ads.

Instagram had about 150 million active users as of August, and roughly 60 million of those were in the United States.

Although the first ads are likely to be photos, video ads will follow. Facebook will be closely monitoring the reaction of users to video ads. If it is neutral or positive, many analysts believe the company will press forward with video ads on Facebook itself, which has 1.2 billion users worldwide.