Tough challenges

Twitter's biggest challenge is capitalising on its position before a competing technology firm tries to commandeer the microblogging market," according to Williams.

"Things are going well and the stakes are really high," Williams said. "We are going to face serious competition."

Another challenge facing Twitter is preserving the company's culture of doing social and environmental good woven as the small firm grows, according to Stone.

"Twitter is two years old and in the global spotlight," Stone said.

"We don't want to be like the child actor that found fame early and grew up all funky and freaky. Part of working at Twitter is giving back to the world."

Stone said it is possible Twitter could go public with an offering of stock, but that he is hoping the company will find more creative ways to fund its growth.

"It sounds silly, with no revenue, to talk about going public, but I wouldn't say that is ridiculous anymore," Stone said.

"Our goal is to change the world. The needs of the platform mean growing bigger. At some point going public may make the most sense."

Zuckerberg said the creation of Facebook boiled down to a Harvard University student with hacker tendencies starting a company with smart friends.

"By the time I got around to building Facebook, I did it in two weeks," Zuckerberg said.

"Launch early and iterate; Facebook is a really good story of that."

The evolution of Facebook has been driven by what members of the online social networking community do at the website and their feedback, according to Zuckerberg.

"We pride ourselves on building stuff quickly," Zuckerberg said. "We have this technology company that is really like a hacker company. My friends are people who really like building cool stuff."

Zuckerberg told the predominately young audience how he was just 19 years old when he left Harvard in 2004 and went to Silicon Valley to build Facebook into a serious technology company.

"The biggest risk you can take is to take no risk," Zuckerberg said. "In an evolving world, if you don't change you lose."