As Facebook grows, expect to see more ads on Instagram

Facebook, the world's largest social network, has steadily built its advertising business to become the world's second-largest digital ad platform after Google.

While Facebook has been introducing Instagram ads slowly — to avoid irritating users by overloading them with commercial messages — the company said in September that it would allow more kinds of ads, including longer video spots, on the photo-sharing service.

The company beat Wall Street estimates on Wednesday by reporting third-quarter net income of $891 million, on revenue of $4.5 billion.

Facebook is also increasingly introducing new ways for its users to share and watch video on the social network, positioning itself against Google's popular YouTube service.

While the company hasn't spelled out plans to make money from those apps, chief financial officer David Wehner told analysts Wednesday that he's confident "there are going to be opportunities" in the future.

Facebook still handles less advertising than Google, its biggest rival, but its share of global spending on digital ads is growing, according to eMarketer.