Facebook's fourth-quarter revenue topped estimates, boosted by the company's advertising business via videos, mobile devices and the Instagram photo-sharing service. Fourth-quarter sales rose to $5.84 billion. The growth was fueled by more people joining the world?s biggest social network, with more than 1.59 billion users logged on every month, especially on smartphones and tablets. About 80 percent of revenue came from mobile devices.

Facebook is offering marketers well-targeted ads across the company?s properties, especially Instagram, which just marked its first full quarter of ad sales across international markets.

Facebook's business highlights for the full year 2015 include the following:

• Revenue - Revenue for the full year 2015 was $17.93 billion, an increase of 44% year-over-year.
• Income from operations - Income from operations for the full year 2015 was $6.23 billion.
• Net income - Net income for the full year 2015 was $3.69 billion.
• Free cash flow - Free cash flow for the full year 2015 was $6.08 billion.
• Daily active users (DAUs) - DAUs were 1.04 billion on average for December 2015, an increase of 17% year-over-year.
• Mobile DAUs - Mobile DAUs were 934 million on average for December 2015, an increase of 25% year-over-year.
• Monthly active users (MAUs) - MAUs were 1.59 billion as of December 31, 2015, an increase of 14% year-over-year.
• Mobile MAUs - Mobile MAUs were 1.44 billion as of December 31, 2015, an increase of 21% year-over-year.
  

Facebook is also trying to expand its business in order to generate income from its newer projects. Oculus Rift, the virtual reality headset, started its first sales to consumers earlier this month. Internet.org, the free Web access initiative for emerging markets, has a widely used Free Basics app, which has already sparked protests in India for being too Facebook-centric.

Facebook has also several properties that are poised to top 1 billion users, including WhatsApp and Messenger. Instagram has more than 400 million users.