Inbound web traffic coming from 'dark social', such as via links from email, forums or instant message, now accounts for 74 per cent all online sharing activity in the UK, according to research from RadiumOne. The 'Light and Dark of Social Sharing- harnessing the power of consumer connections study' , found that activity via dark social, which refers to any online activity which web analytics are unable to track, far outweighs sharing on Facebook (19 per cent)