Evan Williams, the co-founder of Twitter reveals that many of the ideas driving its growth came from unexpected uses invented by the users themselves.

Watch the other TZ picks of the fantastic TED Talks series: Daniel Kahneman - the riddle of experience v memory, Seth Godin on tribes and leadership, Randy Pausch: Really achieving your childhood dreams, JK Rowling - the fringe benefits of failure, The knowledge ecosystem, Fields Wicker-Miurin on Learning from leadership's 'missing manual', Gerver Tulley and his tinkering school, Dan Pink on the science of motivation, TED Talks: Alexis Ohanian on how to make a splash in social media and Tim Ferris: Smash the fear, learn anything, Jamie Oliver -teach out kids about food.

If you would like to nominate a TED Talks - email us: editor@trainingzone.co.uk