Note: We originally posted this item last August. We've updated it and are resurfacing it now, a day after Bill de Blasio was sworn in as mayor of New York. 

Bill de Blasio (D) was sworn in as mayor of New York Wednesday. He vowed to take on a liberal agenda rooted in leveling the playing field for the city's residents, hitting on the theme which was at the center of his campaign.

(Seth Wenig/AP)

So, just who is de Blasio? Below are the five biggest things to know about him:

1. He ran as the most liberal major candidate in the field. De Blasio, a former member of the City Council, positioned himself to the left of the field during the campaign. He sported an endorsement from the left-leaning magazine The Nation, and supported oversight measures for the city's "stop and frisk" law that a judge ruled unconstitutional this week. (He made "stop and frisk" a central focus of his campaign.) The collapse of liberal candidate Anthony Weiner appeared to boost de Blasio's support on the left.

2. De Blasio managed Hillary Clinton's 2000 Senate campaign. De Blasio was Clinton's campaign manager during her first bid for the upper chamber. Know who else worked on the campaign? Howard Wolfson, now a top aide to Mayor Michael Bloomberg (I). As public advocate, the position to which he was elected in 2009, de Blasio's role was to be a city government watchdog of sorts. And that's meant that he hasn't been shy about criticizing Bloomberg's policies. "Bill is a friend," Wolfson told National Journal. "But he has set forth a vision for the city that is very explicit — higher taxes, bigger government, more regulation, more mandates on business, and in my opinion we tried that model and it failed."

3. He changed his name. De Blasio was born Warren Wilhelm. His father fought in World War II and his parents split up early in his life. De Blasio said his dad was in a "downward spiral" when he returned to the U.S., and he was raised by his mother's family, leading him to adopt their last name. "I started by putting the name into my diploma. Then, I hyphenated it legally when I finished NYU. And then more and more, I realized that was the right identity," de Blasio told Public Radio Exchange. What about Warren? De Blasio said he's always been called "Bill."

4. He boasts some celebrity support. Alec Baldwin backs him. So do Sarah Jessica Parker and Cynthia Nixon of "Sex and the City" fame.

5. His family has gotten a lot of attention. De Blasio's teenage son was the sole speaker in his first campaign commercial. De Blasio is married to Chirlane McCray, who is African American. They have two children together. McCray's 1979 essay "I Am a Lesbian" received a lot of attention in the campaign. McCray told Essence magazine last year that she was able to go from coming out as a lesbian to falling in love with de Blasio by "putting aside the assumptions I had about the form and package my love would come in. By letting myself be as free as I felt when I went natural."