@jack exits Twitter

What next for the social media platform after Jack Dorsey quits? the BBC's tech reporter in Silicon Valley James Clayton tells us why Jack Dorsey has left as CEO, and the challenges facing Twitter under new boss Parag Agrawal. Plus Jane Wakefield speaks to an Afghan student turning to the Internet to continue her education under Taliban rule, and we hear from the company forging ahead with plans to deliver Internet networks with balloons, despite Google's abandoning of the project. With BBC tech reporter Shiona McCallum.(Photo: Twitter CEO Jack Dorsey addresses students during at the Indian Institute of Technology (IIT), New Delhi. Credit: Anushree Fadnavis/Reuters)