While Facebook recently disclosed that it has 845 million subscribers, half of which visited the site in December, Google estimates Facebook's actual unique visitor count at a staggering 950 million.
The public data also states that Facebook reaches 50.6 percent of all Internet users. In comparison, the world's second most popular site (excluding Google itself), YouTube, is estimated at 880 million unique visitors and a reach of 46.9 percent. Yahoo, in third, has 600 million unique visitors and a reach of 32 percent.
Facebook generates about 32 billion visits and 920 billion page views per month. During each visit, users are spending about 23 minutes and 20 minutes on Facebook - and return about 30 times per month, on average. If Doubleclick is right, then Facebook records a stunning 1.4 million user-years per month.