Facebook's global revenue is expected to double this year to $4.27 billion, research firm eMarketer said Tuesday.

The Palo Alto, California-based social network is expected to earn $3.8 billion worldwide this year in advertising revenue, eMarketer said, up 104 percent from the $1.86 billion it raked in last year.

The research firm also said revenue from Facebook Credits, the currency used on the site, is estimated to reach $470 million, up from $140 million last year.

"Facebook's revenue streams will continue to diversify, with ads representing a decreasing proportion of total revenue while other sources such as Facebook Credits will grow," eMarketer principal analyst Debra Aho Williamson said in a statement.

Facebook will earn $5.78 billion in worldwide ad revenue in 2012, eMarketer estimated.

As a privately held company Facebook does not disclose figures on its financial performance.

Facebook, the world's largest social network with more than 750 million members, is expected to go public next year and would have to open its books to conduct an initial public offering.

Facebook finetunes news feeds from friends
San Francisco (AFP) Sept 20, 2011 - Facebook on Tuesday began rolling out the latest in a rapid-fire series of enhancements to the leading social network as nascent rival Google+ opened its membership to the world.

Facebook's "News Feed" that streams updates from friends will give priority to important posts, images shared at the website will be displayed larger, and a "Ticker" chat column is being added for real-time conversations.

"As Mark (Zuckerberg) put it, this is launching season," Facebook product manager Keith Schacht told AFP while discussing the new features.

"This is an update we have been working on a long time, unrelated to anything else," Schacht responded when asked whether the launch of rival Google+ in June was a factor behind the recent barrage of Facebook features.

In recent weeks, Facebook has focused on ways for members to better control what information gets shared with whom.

Facebook last week began letting members follow strangers Twitter-style with the addition of "Subscribe" buttons that let people hear from people who aren't friends at the network, and share insights with strangers.

Facebook also began letting members be more selective about what kinds of updates from friends make it into their personal news feeds.

"Last week we announced (Smart) List and Subscribe, which were about more control of what members see in the News Feed," Schacht said. "Today, these changes are about letting people see the most important news."

If a Facebook user hasn't visited the social network for a few days, the news feed will prominently display significant posts from friends that may have been missed during that time away.

Someone who frequently checks their Facebook account will have recent happenings at the top of his or her news feed.

"If you didn't read the newspaper for three days, then on Day Four you pick up a newspaper how awesome would it be if the front page summarized the news from the past three days?" Schacht asked.

"Facebook will get better over time at understanding what is important to each person," he said. "If we are wrong, you can tell us."

The latest enhancement to photo viewing at Facebook increases the size of uploaded images. About 250 million photos are uploaded daily to the social network.

The new "Ticker" chat panel in a right-hand column on the screen allows people to engage in text chats focused on freshly uploaded images or other posts.

"News Feed is an historical view of what your friends have shared," Schacht said. "Ticker is about real-time exchanges with friends."

Facebook planned to begin rolling out the new features globally Tuesday and expected them to reach all of its more than 750 million users within a week.

More Facebook announcements are expected at the social network's annual developers conference taking place in San Francisco on Thursday.

The gathering will come just days after Google dropped the need for an invitation to join the Internet giant's challenge to Facebook, Google+.

"For the past 12 weeks we've been in field trial, and during that time we've listened and learned a great deal," Google senior vice president of engineering Vic Gundotra said Tuesday.

"We're nowhere near done, but with the improvements we've made so far we're ready to move from field trial to beta... Anyone can visit google.com/+, join the project and connect with the people they care about."

Fresh enhancements to Google+ included letting members take part in video-chat "Hangouts" using camera-enabled smartphones or tablet computers, or broadcast video presentations to groups of watchers using "Hangouts On Air."

Google said it has also woven its Internet search expertise into the social network by adding a query box.

Google+ combined aspects of Facebook and microblogging sensation Twitter, and promised users that sharing aspects of their lives at the social network would reflect levels of confidentiality granted in real life.

Google+ stresses the ability it gives users to separate online friends and family into different "Circles," or networks, and to share information only with members of a particular circle.

Google is hoping its billion users worldwide are drawn into the California-based Internet giant's social network.