LinkedIn hit a milestone today: the professional network has doubled in size at 200 million members. The company had hit the 100 million member mark in 2011.

New features added in 2012 were aimed at businesses and advertisers, including redesigned company pages, targeted status updates, an ads API program, and self-serve video ads.

The niche network is still behind other popular sites in sheer numbers — Facebook has more than 1 billion members. The second largest network, Twitter, has approximately 640 million members.

But LinkedIn has been consistently profitable since its stock market debut in 2011, drawing revenue from its hiring solutions, marketing solutions, and premium subscriptions. The company reported $252 million in revenue and $2.3 million in profits for the third quarter of 2012.

Today, LinkedIn has provided an overview of its member base in the form of an infographic. Information technology professionals are currently dominating the network with 4 million members. The United States has the largest presence on LinkedIn with 74 million members, but the company reports rapid growth in Turkey, Colombia, and Indonesia.