Jack Dorsey: “My entire focus is to make sure that Twitter is going to be amazingly successful.”  Photograph: Justin Tallis/AFP/Getty Images

For the past two years, the normally dapper Jack Dorsey has hardly been seen at the offices of Twitter, the social networking company he co-founded, e(...)

Outgoing Twitter chief executive Dick Costolo’s impending departure has been influenced by investors unhappy with stagnant user growth and the absence of profit. Photograph: Richard Perry/The New York Times

Some shock waves went through Silicon Valley this week when Twitter chief executive Dick Costolo abruptly announced he was stepping down. The microbl(...)

  Dick Costolo, Twitter’s embattled chief executive, at the New York Stock Exchange during the company’s market debut. Photograph: Richard Perry/The New York Times

Twitter chief executive Dick Costolo abruptly announced he was stepping down on Thursday amid increasing scrutiny of the company’s slow user growth an(...)

Teaforthree (foreground) jumps the last on the way to finishing third in the 2013 Grand National at Aintree.  Photograph: Adrian Dennis/AFP/Getty Images.

Plans are on hold for Teaforthree after he missed a run at Warwick yesterday because of a bruised foot. The 11-year-old was set to compete in the Will(...)

The British hunt season is well under way and continues at Sandown on Saturday.

Balder Succes will face nine rivals when he bids to justify favouritism in the Tingle Creek Chase at Sandown on Saturday.With star two-milers Sprinter(...)

 It may surprise, but tech gurus are limiting the amount of screen time their children get. Photograph: Anders Andersson/Getty

When Steve Jobs was running Apple, he was known to call journalists to either pat them on the back for a recent article or, more often than not, expla(...)

Some of Twitter’s biggest investors are hanging on to their stock, even as restrictions on selling the shares are set to lift today. About 480 million(...)

Denis O’Brien grew his wealth by $800 million last year, according to Forbes, making him the second richest person in Ireland and the 234th in the world with a fortune of $6 billion. Photograph: David Sleator/The Irish Times

Denis O’Brien, the telecoms and media entrepeneur, added $800 million (€579m) to his fortune in 2013, according to the just published Forbes Bi(...)

Web Log

And you thought Justin Bieber was a manufactured pop act. Z-Machines literally is. This band of robots plays their own instruments. They jam harder wh(...)

None of Twitter’s founders comes off well in Nick Bilton’s absorbing book about the creation of the social media firm. Kacper Pempel/Reuters.

Is there some rule that the founders of social networks have to behave so anti-socially? The twists, turns and double-crosses in Hatching Twitter, Nic(...)