The other half of the social networking big two, Twitter continues to go from strength to strength with 140 million tweets now sent every day, up from 50 million in March 2010. 

The micro-blogging phenomenon is also redefining the way news is reported and consumed with constant 140-character updates on big stories making information instantaneous and all but impossible to censor. It's also proved an invaluable tool for protestors in Egypt, Libya and elsewhere.
 
Twitter upped its game in 2011, releasing fantastic iPhone, Android and iPad apps that now finally eclipse the third-party clients on offer. Twitter is a service that defines the Web 2.0 generation of tech.