San Francisco, May 17 (IANS): Twitter co-founder Biz Stone, who left the company in 2011, is rejoining the company as a full-time employee.

"My top focus will be to guide the company culture, that energy, that feeling. It's important that everyone understands the whole story of Twitter and each of our roles in that story. I'll shape the experience internally so it's also be felt outside the company," Stone wrote in his blog post on Tuesday.

Stone recently sold his startup Jelly to Pinterest.

It is still not clear what Stone's title will be but according to ReCode, he will report to Twitter Chief Marketing Officer Leslie Berland and help with internal communications and morale at the company.

With Stone's return, Twitter now has two of its co-founders back, with a third, Evan Williams, sitting on the board.

According to Stone's post, his decision to return was surprising even to him.

CEO Jack Dorsey apparently asked him to return while Stone was visiting the company's all-hands gathering, called Tea Time, a few weeks back.

"I wasn't really sure if he meant it," Stone wrote.

"After Tea Time, we spoke privately and Jack told me that he really did -- he wanted me to come back and work at Twitter. The company I co-founded, the service I co-invented. I was stunned, but I knew the answer," he added.