Barack Obama joins dozens of presidents, prime ministers and even the pope by now tweeting from a new account described as his personal feed. It launched last week as @POTUS, which stands for President of the United States. Last week's first tweet from the Oval Office says: "Hello, Twitter! It's Barack. Really! Six years in, they're finally giving me my own account." Only five more tweets followed in the next six days. (The man is pretty busy, after all.)

Heads of government increasingly use Twitter as a tool to spread messages and gain support for policies. There's even a term for this form of digital diplomacy: Twiplomacy. A notable exception to the trend is German Chancellor Angela Merkel, who’s not on Twitter. Of course, most tweets "from" world leaders are drafted by social media aides carefully considering every phrase. "This isn't going to change the world," says Dan Pfeiffer, a former top adviser to Obama. "But the way the President of United States communicates with his constituents changed forever today [May 19] and that's a big deal."

Obama's new feed is separate from a @BarackObama account that has nearly 60 million followers and is run by his campaign spin-off group, Organizing for America. There's also a @WhiteHouse feed overseen by the communications staff. The @POTUS account has 2.4 million followers as of Memorial Day, and will be passed from president to president as a new chief executive arrives. And just to put those numbers in perspective: @katyperry has 70 million followers, while @justinbieber has 64 million.

Past White House adviser says: "The world has changed. Twitter is now a place a president needs to be if he or she want to respond to events, make news and talk to the public." – Dan Pfeiffer

Blogger says: "We shouldn't expect Obama to be particularly prolific with his tweets, nor should we expect them to offer any nuanced looks into the man writing them." – Robert Montenegro at bigthink.com

Reporter says: "For a president, Twitter is just one more avenue in which your every move will become politicized." – Josh Linkins, Huffington Post