It was celebration time for Facebook, which achieved yet another milestone on 4 Feb, when it completed its fifth year. Yes, the Palo Alto, California based social networking website celebrated its fifth birthday on Wednesday.

Founded on February 4, 2004 at Cambridge, Massachusetts, Facebook is the number one social networking websites today. According to online research firm ComScore Inc., Facebook has recently edged out its rival MySpace. com, in the number of unique visitors; Facebook got almost 222 million unique visitors in December, while MySpace got 125 million.

In a blog post, Facebook CEO Mark Zuckerberg wrote, "Facebook was founded in 2004 to give people the tools to engage and understand the world around them. We are glad and humbled that so many people are using Facebook in this way."

Expressing his exhilaration on Facebook's fifth birthday, Zuckerberg wrote, "This is a happy occasion for Facebook, but much more significant to the Facebook team is the fact that over 150 million people around the world are using Facebook to connect with the people in their lives."

Announcing a surprise gift, slated to be available in the Facebook Gift Shop, which users can send to their pals on the site, Zuckerberg wrote, "In the spirit of celebrating connections between people, we encourage you to use this gift to give thanks to your friends, colleagues and family members with whom you are connected on Facebook."

On the fifth birthday of Facebook, Hitwise Pty. Ltd., the Internet monitoring firm released the social networking website's current statistics. According to Hitwise, Facebook's market share doubled, from 15% in January 2008 to 31% in January 2009, the month in which that Facebook had the fifth-highest market share of all Web sites.